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f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.2.5.3 Receipt of a REFER request outside a session | If a REFER is received outside a dialogue, this may occur in case of a recall procedure, the PES Endpoint acts according the method parameter in the Refer-To header with simultaneous consideration of the URI of the Refer-To header. In this context if a "m" parameter is received containing the values "BS or NR", this indication for the Call Completion recall may be used to inform the user about this event. This indication may be used to select a ring pattern conforming to a "distinctive" ring signal. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.2.6 Charging procedures | A PES access point supporting advice of charge services shall support the INFO method and shall accept MIME bodies of type "application/vnd.etsi.aoc+xml". If the PES access point transmits an INFO request including a body (part) with AOC information, then ythe Content-Type header field shall include "application/vnd.etsi.aoc+xml", the MIME type associated with AOC information (see annex E), and the "sv" or "schemaversion" parameter's value shall be set to the - versions of AOC XML Schema that can be used to validate the AOC information XMLdocument. One of the versions of the MIME type associated with AOC information (see annex E) - indicated shall correspond with a value of the version attribute of the <schema> XML element of an AOC XML Schema (see e.g. annex E). If the "sv" and "schemaversion" parameter are absent, the PES access point shall assume that version 1 of the XML Schema for the AOC information XML body is supported. If both the "sv" and "schemaversion" parameters are present, then the PES access point shall use the "sv" parameter. In multiple call leg scenarios like three way conversation or conference calls the PES access point shall process charging information received from the PES Application server as described in clause 5.3.3.6: • The charging information shall be assumed to be received for each call leg separately from the PES Application Server. The PES access point has to combine the AOC information received from the PES Application Server. • As a network operator option the charging information received may be assumed as a combined representation applying to all call legs. The PES access point simply applies the last received charging information to the served user. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.2.7 Supplementary services configuration | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.2.7.1 Analogue lines | Analogue subscribers can control their supplementary services using service code commands as defined in ETS 300 738 [12] included in the user part of the Request-URI of an INVITE message. Further details are provided in annex C. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.2.7.2 ISDN lines | ISDN subscribers can configure supplementary services using procedures applied at either the Gm reference point or the Ut reference point. In the case of the Ut reference point, HTTP PUT, HTTP GET or HTTP DELETE requests are used in accordance with RFC 4825 [i.1] and the supplementary services application usage specified in TS 124 623 [33]. In case of the Gm reference point two procedures are available: • Use of service code commands as for analogue subscribers, when ISDN stimulus procedures are used by the end user terminal. • Use of the MESSAGE method when ISDN functional procedures are used by the end user terminal. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 32 The MESSAGE method is used to convey the service related information to the relevant target. The information to configure a service is embedded in an XML instance document contained in the MESSAGE request as specified in TS 183 036 [40]. The P-Asserted-Identity shall be set as specified in clause 5.3.2.4 for an INVITE request. The To and From headers shall be set to the public user identity associated to the supplementary service action. This public user identity may be built from the line or access identifier (e.g. line-identifier@pes.operator.com) or be a directory number obtained by the PES Endpoint through provisioning or at registration in case of line-based registration. When receiving a MESSAGE request conveying a response to an ISDN supplementary service interrogation procedure (see TS 183 036 [40]), the PES access point shall look for the In-Reply-To header field and evaluate its contents to identify the initial MESSAGE request to which it is responding. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3 PES Application Server | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.1 General | In addition to the procedures specified in the rest of clause 5.3.3, the PES application server shall support the procedures specified in TS 124 229 [4] appropriate to an application server. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.2 Basic call procedures | A PES application server can act either as a proxy server or as a Back to Back User Agent (B2BUA) while processing calls. When acting as a B2BUA, the PES application server provides both originating UA and terminating UA functions as described in TS 124 229 [4]. As an originating UA that sends outbound INVITE requests, the PES application server must appropriately handle responses received from a forking proxy and must appropriately interwork provisional and final INVITE responses, as well as other SIP requests, between the originating UA and terminating UA functions employed on a single call. When handling an outgoing call, the PES application server shall populate the "cpc" URI parameter in the contents of the P-Asserted-Identity header as defined in TS 124 229 [4] in each INVITE request, unless the parameter value is "ordinary". How the PES application server determines the value of this parameter (UPSF query, local configuration data, etc.) is outside the scope of the present document. When handling an outgoing call, the PES application server shall override the P-Asserted-Identity with a meaningful public user identity (i.e. a Directory number) in each INVITE request if the received P-Asserted-Identity is derived from an analogue line or ISDN access identifier or represents a gateway. The PES application server determines this meaningful identity from the contents of the P-Asserted-Identity using provisioned mapping table. If a P-Access-Network-Info header field containing the location of the calling line is received without the "np" parameter and the PES AS has the knowledge that the request comes from a trusted A-VGW, it may decide to insert an "np" parameter in it and remove any other P-Access-Network-Info header field that contains the location of this VGW. When handling an incoming call, the PES application server shall rewrite the To header field with s URI containing either an entity representing the target line/access if group registration was used and directory numbers have not been provisioned on the PES access point / PES endpoint, or otherwise the identity received in the Request-URI. In the first case, the PES application server determines the identity to be included in the To header field using a provisioned mapping table. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.3 Announcement procedures | The PES application server shall have the capability of requesting announcements during any phase of a session, according to the procedures described in TS 124 628 [6]. The PES application server shall use the ANNC URL syntax defined in [16] when requesting a PES announcement server to play an announcement. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 33 A PES application server acting as a B2BUA must appropriately handle received Call-Info, Alert-Info, and Error-Info headers that contain requests to play announcements, as defined in TS 124 628 [6]. Depending on the application, this may mean relaying the header toward the originating PES endpoint or PES access point, connecting the originating UE to an MRF, or ignoring the announcement request and providing some other call processing (such as with a simultaneous ringing application that ignores failure announcements from unsuccessful call legs). When sending announcements during the call setup phase, the PES application server shall include a P-Early-Media header set according to TS 124 628 [6]. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.4 Profile Delivery | The PES application server shall act as a profile delivery server and manage Profile documents whose structure conforms to the XML schema defined in annex A and TS 124 623 [33]. The contents of the NOTIFY request shall be as follows: • The Event header shall be set to the "ua-profile" event package. • The "effective-by" parameter for the event header shall be set to 0. • The content type shall be set to "application/simserv+xml". In case of implicit subscription the first NOTIFY message is sent when the current profile differs from the network's default profile. Changes to these documents shall be notified by reporting the "ua-profile" event defined in [15]. How the PES server keeps track of changes to these documents is outside the scope of the present document. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.5 Transport of ISUP information | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.5.1 General | Clause 5.3.3.5 describes the general behaviour of the PES application server in the case the PES application server is capable of exchanging ISUP information, as defined in ITU-T Recommendation Q.763 [29], carried within Narrowband Signalling Syntax (NSS) [31] message bodies with its SIP signalling peers to perform service related signalling that is capable of interworking with PSTN services. Clause C.1.4 lists examples of services some of which may require the use of encapsulated ISUP information. The sending or receiving of ISUP information in NSS message bodies is applicable to any of the following roles of the Application Server: • PES application server acting as terminating UA or redirect server. • PES application server acting as originating UA. • PES application server performing 3rd party call control. The procedures defined in the following clauses allow a PES application server to discover whether or not its peer SIP signalling entity (i.e. the next UA along the signalling path, which may be a B2BUA, and therefore excluding any intermediate proxies) is capable of supporting NSS message bodies within SIP messages, and to successfully support the additional exchange of ISUP information needed for those services supported in common by endpoints supporting potentially different sets of services. Each IMS PES must assure that NSS message bodies are not forwarded to UEs and are not forwarded to untrusted SIP networks according to local policy. Clause 5.3.3.5.2.4 describes the role of the PES application server in maintaining NSS security. NOTE: Services that require manipulation of the ISUP information within NSS message bodies cannot be implemented on application servers acting as a SIP proxy. The PES application server shall support parameter translations and defaults defined in TS 129 163 [32] for the ISUP information needed for supported services. The PES application server shall also send each piece of ISUP information in the appropriate SIP message so as to allow the valid interworking with the corresponding PSTN services according to TS 129 163 [32]. The PES application server shall not include in NSS message bodies any ISUP information that is already represented by SIP signalling. The handling of forked requests with NSS message bodies is for further study. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 34 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.5.2 Sending NSS message bodies to a peer SIP signalling entity | 5.3.3.5.2.1 General The PES application server shall send an NSS message body with encapsulated ISUP information in the appropriate SIP message to a peer SIP signalling entity according to the clauses 5.3.3.5.2.2 through 5.3.3.5.2.7, when all the following conditions are satisfied. • The PES application server is capable of performing service related signalling using ISUP information for one or more of the services it supports. • An event associated with one of the supported services occurs that requires that ISUP information be sent to the peer SIP signalling entity. This event may be the receipt of signalling information from another SIP interface to the PES application server, or a service event internal to the PES application server. • Either the encapsulating message is the initial INVITE request, or the peer SIP signalling entity has previously indicated support for NSS message bodies within the associated dialog (see clause 5.3.3.5.2.2). • The SIP signalling in the encapsulating message cannot represent the information, and the information is different from the default values defined in TS 129 163 [32]. NOTE: Information may be duplicated in the NSS and vnd.etsi.pstn XML MIME bodies. 5.3.3.5.2.2 Determining support for NSS message bodies When constructing an initial INVITE request, an originating PES application server that supports any services that require encapsulated ISUP information shall include an indication of support for NSS by including an Accept header in the initial INVITE request that indicates support for NSS ("application/nss") according to clause 5.3.3.5.2.3. Until the originating PES application server receives an indication of support for NSS message bodies from its peer SIP signalling entity (by receipt of a SIP message that either includes an Accept header indicating support for NSS or an NSS message body), the originating PES application server shall not send any further NSS message bodies within the dialog. If a terminating PES application server receives an initial INVITE request that does not include an Accept header indicating support for NSS, the terminating PES application server shall not send NSS message bodies within the dialog. If a terminating PES application server supporting any services that require the signalling of ISUP information receives an initial INVITE request that includes an Accept header indicating support for NSS, the terminating PES application server shall indicate support of NSS in the first SIP message to its SIP signalling peer. The terminating PES application server indicates support of NSS using the Accept header if allowed in the SIP message. Otherwise, the terminating PES application server does this by including an NSS message body in the SIP message. In the later case, if there is no need to send ISUP information to the SIP signalling peer in the first SIP message, the terminating PES application server shall send a generic parameter list (GPL) NSS message with no parameters. A terminating PES application server not supporting NSS will follow procedures in clause 5.3.3.5.3.1. 5.3.3.5.2.3 NSS message bodies The PES application server shall format the NSS message body according to ITU-T Recommendation Q.1980.1 [31]. The Content-Type header field associated with the NSS message body shall be included as follows: • Content-Type: application/nss. The Content-Disposition header field associated with the NSS message body shall be set in one of the following two ways (see clause 5.3.3.5.2.7): • Content-Disposition: signal; handling = required; or • Content-Disposition: signal; handling = optional. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 35 5.3.3.5.2.4 ISUP information security If network entities in the IMS PES cannot be relied on to provide ISUP information confidentiality and integrity, then the PES application server shall not send NSS message bodies or process received NSS message bodies (other than ignoring or rejecting any NSS message bodies). A PES application server acting as routeing B2BUA shall remove NSS message bodies and indications of NSS support (e.g. an NSS entry in the Accept header) from SIP messages being forwarded towards each UE. If a PES application server is assigned to remove the NSS message bodies from SIP messages being forwarded to a UE, then the PES application server shall be configured within the terminating filter criteria for its UE. 5.3.3.5.2.5 Determining in which message to encapsulate ISUP information If a service logic event coincides with one of the SIP basic call control messages, i.e. INVITE request, re-INVITE request, BYE request, UPDATE request, or responses to these messages, any required ISUP information shall be encapsulated in the corresponding SIP message. If a service logic event requiring the sending of ISUP information occurs that does not coincide with one of the SIP basic call control messages, the PES application server shall send the ISUP information encapsulated in an INFO request or a 183 (Session Progress) response, as described below. An originating PES application server cannot send an INFO request until it receives a reliable provisional response or final response. A terminating PES application server cannot send an INFO request until a reliable provisional response or final response has been sent by the PES application server and the response has been acknowledged. If service logic requires an NSS message body marked with optional handling (see clause 5.3.3.5.2.7) to be sent before an INFO request can be sent, the terminating PES application server may send the NSS message body in a 183 (Session Progress) reliable response. If the service logic requires an NSS message body marked with required handling to be sent before an INFO request can be sent, the terminating PES application server shall first send a 183 (Session Progress) reliable response without an NSS message body and wait for acknowledgment of the response before sending the NSS message body in the INFO request. 5.3.3.5.2.6 Determining the NSS message identifier code If the ISUP information included in the NSS message body uniquely identifies the ISUP message needed to interwork the ISUP information to an ISUP interface, or if the interworking with ISUP is unambiguously identified by the SIP signalling and/or the encapsulated ISUP information, the PES application server shall include the ISUP information in an NSS GPL message. Otherwise, the PES application server shall include an explicit ISUP message name in the NSS message body. 5.3.3.5.2.7 Determining the content disposition handling 5.3.3.5.2.7.1 Content disposition for the initial INVITE request A PES application server sending an INVITE request with an NSS message body shall mark it for required handling (see clause 5.3.3.5.2.3) if the service logic requires the peer SIP signalling entity to understand the ISUP information. Otherwise, the PES application server shall mark the NSS message body in the initial INVITE request for optional handling. If the peer SIP signalling entity is unable to process an NSS message body marked for required handling in an initial INVITE request, it will reject the INVITE request with a failure response, allowing the originating PES application server, or perhaps a proxy on the path, to optionally retry the request to an alternate destination that may be capable of handling the NSS message body. 5.3.3.5.2.7.2 Content disposition for the INFO request A PES application server sending an INFO request with an NSS message body shall mark it for required handling if the service logic requires the peer SIP signalling entity to understand the ISUP information. Otherwise, the PES application server shall mark the NSS message body in the INFO request for optional handling. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 36 If the peer SIP signalling entity rejects an NSS message body in an INFO request by returning a failure response, the PES application server performs the service procedure that applies when unable to signal ISUP information, if such a procedure exists, and continues the call associated with the parent dialog. The PES application server shall release the call if the INFO request fails and there is any ISUP information in the INFO request that requires call release if it cannot be processed or forwarded. 5.3.3.5.2.7.3 Content disposition for other SIP messages If the previous clauses do not apply, the PES application server shall mark the NSS message body in the SIP message for optional handling. NOTE: A PES application server sending an NSS message body in any SIP response message will mark it for optional handling, since the peer SIP signalling entity cannot reject the message. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.5.3 Receiving an NSS message body from a peer SIP signalling entity | 5.3.3.5.3.1 General On receipt of a SIP message containing an NSS message body, a PES application server supporting services that require encapsulated ISUP information shall de-encapsulate the ISUP information from the NSS message body, perform the processing described in the clause 5.3.3.5.3.2, and trigger the relevant service logic. If the PES application server does not receive ISUP information required by the service logic, the service logic defines the PES application server behaviour, e.g. by assuming default values defined by the service logic. 5.3.3.5.3.2 ISUP compatibility procedures A PES application server shall reject with a SIP 603 (Decline) response a SIP request that includes an NSS message body that is marked for required handling, that includes ISUP information that the PES application server does not support, and that either includes no compatibility parameter for the unsupported information, or includes a compatibility parameter for the unsupported information that requires release when the parameter is unsupported. Otherwise, the PES application server shall ignore any unsupported ISUP information. The PES application server may ignore any unsupported ISUP information it receives in an NSS message body marked for optional handling or perform any other behaviour determined by the service logic. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.6 Handling of charging information | When processing originating sessions, the PES application server shall be able to act as a Charging Generation Point (CGP) and send the appropriate charging information to the PES access point/endpoint. The PES application server shall accept charging information in the format defined in TS 129 658 [42], annex C and may accept charging information received as part of an NSS body (see clause 5.3.3.5). When processing originating sessions, the PES application server shall be able to insert advice of charge information in SIP messages sent to the calling user, using the mechanism described in TS 124 647 [7]. When processing originating sessions with multiple call legs to be charged, e.g. in 3-party calls or when using the conference service, then the PES Application server shall send related charging information to the PES access point/endpoint separately for each call leg. As a network operator option the PES application server may send charging information related to the affected call legs in a combined representation in a single AOC XML body. • When only one dialog is active between the UE and the application server, or after network-based conference has been used (as defined in ETSI 24.605) and the UE is left with just one dialog to the conferencing MRF, the AS may use this method since separate dialogs no longer exist for each far party. • If only one dialog exists between the PES access point/endpoint and the PES application server, the PES access point/endpoint is not informed when one of the far parties is released. In order to ensure that charging is accurate, the PES application server will have to send an INFO request with an XML body each time a far party is added or released. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 37 When processing terminating sessions, the PES application server may be able to act as a Charging Determination Point (CDP) and send charging information to the calling user using the format defined in TS 129 658 [42], annex C. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.3.7 Supplementary services configuration | Three modes of operation may be supported depending on the type access and the operator's policy: • Service code commands received in the Request-URI of INVITE message at the ISC reference point. • XML documents received in HTTP PUT, HTTP GET or HTTP DELETE requests received at the Ut reference point in accordance with RFC 4825 [i.1] and the supplementary services application usage specified in TS 124 623 [33]. • XML documents received in MESSAGE messages as specified in TS 183 036 [40]. When sending a MESSAGE request in response to another MESSAGE request, the PES AS shall set the In-Reply-To header field value to the value of the Call-ID header field received in the incoming request. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.4 PES Announcement Server | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.4.1 General | In addition to the procedures specified in the rest of clause 5.3.4, the PES announcement server shall support the procedures specified in TS 124 229 [4] appropriate to an MRFC. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.4.2 Announcement procedures | The PES announcement server shall support the ANNC URL syntax defined in [16] when providing announcements, prompt and collect functions, and multi-party conferencing. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5 PES Interworking Application | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.1 General | In addition to the procedures specified in the rest of clause 5.3.5, the PES interworking application shall support the procedures specified in TS 124 229 [4] and TS 124 628 [6] appropriate to an MGCF. The PES interworking application shall support the P-Early-Media header. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.2 Routing procedures | In case of incoming calls from legacy networks, the PES interworking application determines the next hop in IP routing depending on received signalling information, based on configuration data and/or data base look up. The next hop may be an I-CSCF, a BGCF or an IBCF. Based on the destination and local policy rules, the PES interworking application may include ISUP information in the messages sent to the next entity, as described in clause 5.3.5.4. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.3 Handling of charging information | The PES interworking application shall be able to insert charging information in SIP messages sent to the calling user, based on charging information received from the PSTN. The PES interworking application shall use the format defined in TS 129 658 [42], annex C. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 38 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.4 Transport of ISUP information | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.4.1 General | The procedures in the clause 5.3.5.4 allow the PES interworking application to discover whether or not its peer SIP signalling entity is capable of supporting the encapsulation of ISUP information in Narrowband Signalling Syntax (NSS) [31] message bodies within SIP messages, and to successfully support the additional exchange of ISUP information needed for those services supported in common by endpoints supporting potentially different sets of services. These procedures are based on TS 129 163 [32] with the extended capabilities described in the present document. When signalling ISUP information within a SIP dialog, the PES interworking application shall act as either a Type A or Type B exchange depending on the role (e.g. gateway between operators, transit) the PES interworking application is performing for that particular call and the ability to exchange ISUP information during the call. Clause C.1.4 lists examples of services some of them may require the use of encapsulated ISUP information. Each IMS PES must assure that ISUP information is not shared with UEs and untrusted SIP networks according to local policy. Clause 5.3.5.4.2.4 describes the PES interworking application's role in maintaining NSS security. The PES interworking application shall support parameter translations and defaults defined in TS 129 163 [32] for the ISUP information needed for supported services. The PES interworking application shall also send each piece of ISUP information in the appropriate SIP message so as to allow valid interworking with the corresponding PSTN services according to TS 129 163 [32]. The PES interworking application shall not include in NSS message bodies any ISUP information that is already represented by SIP signalling. The handling of forked requests with NSS message bodies is for further study. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.4.2 Sending ISUP information to a peer SIP signalling entity | 5.3.5.4.2.1 General The PES interworking application shall send an NSS message body with encapsulated ISUP information in the appropriate SIP message to a peer SIP signalling entity according to the clauses 5.3.5.4.2.2 through 5.3.5.4.2.7, when all the following conditions are satisfied. • Either the encapsulating message is the initial INVITE request, or the peer SIP signalling entity has previously indicated support for NSS message bodies within the associated dialog (see clause 5.3.5.4.2.2). • An event occurs requiring signalling to the peer SIP signalling entity. This event may be the receipt of an ISUP message from the PSTN, or an event internal to the MGCF. • According to local configuration, selected ISUP information shall be encapsulated and sent towards the peer SIP signalling entity. • The SIP signalling in the encapsulating message cannot represent the information, and the information is different from the default values defined in TS 129 163 [32]. NOTE: Information may be duplicated in the NSS and vnd.etsi.pstn XML MIME bodies. 5.3.5.4.2.2 Determining support for NSS message bodies When constructing an initial INVITE request, the O-MGCF supporting NSS message bodies shall include an indication of support for NSS by including an Accept header in the initial INVITE request that indicates support for NSS ("application/nss") according to clause 5.3.5.4.2.3. Until the O-MGCF receives an indication of support for NSS message bodies from its peer SIP signalling entity (by receipt of a SIP message that either includes an Accept header indicating support for NSS or an NSS message body), the O-MGCF shall not send any further NSS message bodies within the dialog. If an I-MGCF receives an initial INVITE request that does not include an Accept header indicating support for NSS, the I-MGCF shall not send NSS message bodies within the dialog. If an I-MGCF supporting NSS receives an initial INVITE request that includes an Accept header indicating support for NSS, the I-MGCF shall indicate support of NSS in the first SIP message to its SIP signalling peer. The I-MGCF indicates support of NSS using the Accept header if allowed in the SIP message. Otherwise, the I-MGCF does this by including an NSS message body in the SIP message. In the later case, if there is no need to send ISUP information to the SIP signalling peer in the first SIP message, the I-MGCF shall send a generic parameter list (GPL) NSS message with no parameters. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 39 5.3.5.4.2.3 NSS message bodies The PES interworking application shall format the NSS message body according to ITU-T Recommendation Q.1980.1 [31]. The Content-Type header field associated with the NSS message body shall be included as follows: • Content-Type: application/nss. The Content-Disposition header field associated with the NSS message body shall be set in one of the following two ways (see clause 5.3.5.4.2.7): • Content-Disposition: signal; handling = required; or • Content-Disposition: signal; handling = optional. 5.3.5.4.2.4 ISUP information security If network entities in the IMS PES cannot be relied on to provide NSS confidentiality and integrity, then the PES interworking application shall not send NSS message bodies or process received NSS message bodies (other than ignoring or rejecting any NSS message bodies). 5.3.5.4.2.5 Determining in which SIP message to encapsulate ISUP information If an event requiring the sending of ISUP information coincides with one of the SIP basic call control messages, i.e. INVITE request, re-INVITE request, BYE request, UPDATE request, or responses to these messages, any required ISUP information shall be encapsulated in the corresponding SIP message. If an event requiring the sending of ISUP information occurs that does not coincide with one of the SIP basic call control messages, the AS shall send the ISUP information encapsulated in an INFO request or a 183 (Session Progress) response, as described below. Clause 5.3.5.4.4 describes events unrelated to SIP basic call control messages that may require the sending of ISUP information. An O-MGCF cannot send an INFO request until it receives a reliable provisional response or final response. An I-MGCF cannot send an INFO request until a reliable provisional response or final response has been sent by the I-MGCF and the response has been acknowledged. If an event requires an NSS message body marked with optional handling (see clause 5.3.5.4.2.7) to be sent before an INFO request can be sent, the I-MGCF may send the NSS message body in a 183 (Session Progress) reliable response. If an event requires an NSS message body marked with required handling to be sent before an INFO request can be sent, the I-MGCF shall first send a 183 (Session Progress) reliable response without an NSS message body and wait for acknowledgment of the response before sending the NSS message body in the INFO request. 5.3.5.4.2.6 Determining the NSS message identifier code If the ISUP information included in the NSS message body uniquely identify the ISUP message needed to interwork the ISUP information to an ISUP interface, or if the interworking with ISUP is unambiguously identified by the SIP signalling and/or the encapsulated ISUP information, the PES interworking application shall include the ISUP information in an NSS GPL message. Otherwise, the PES interworking application shall include an explicit ISUP message name in the NSS message body. 5.3.5.4.2.7 Determining the content disposition handling 5.3.5.4.2.7.1 Content disposition for the initial INVITE request An O-MGCF sending an initial INVITE request with an NSS message body shall mark it for required handling (see clause 5.3.5.4.2.3) in any of the following cases: • The ISUP preference indicator received from the PSTN is set to "ISUP required all the way". • The parameter compatibility parameter associated with any ISUP parameter in the NSS message body indicates "release call" or "discard message" when pass on is not possible. • As a matter of local policy. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 40 Otherwise, the O-MGCF shall mark the NSS message body in the initial INVITE request for optional handling. If the peer SIP signalling entity is unable to process an NSS message body marked for required handling in an initial INVITE request, it will reject the INVITE request with a failure response, allowing the O-MGCF, or perhaps a proxy on the path, to optionally retry the request to an alternate destination that may be capable of handling the NSS message body. 5.3.5.4.2.7.2 Content disposition for the INFO request If an event occurs requiring the sending of an NSS message body, the event does not coincide with one of the SIP basic call control messages (see table 3 in clause 5.3.5.4.4.1), and any failure procedures are defined when unable to pass on ISUP information in the NSS message body to the peer SIP signalling entity, the PES interworking application shall mark the NSS for required handling. For example, the "Interactions with other networks" clause of each relevant supplementary service specification (see table C.1) specifies the PES interworking application procedures when unable to pass on ISUP information. Otherwise, the PES interworking application shall mark the NSS message body for optional handling. Otherwise, the O-MGCF shall mark the NSS message body in the INFO request for optional handling. If the peer SIP signalling entity rejects an NSS message body in an INFO request by returning a failure response, the PES interworking application performs the service procedure for failing to pass on the ISUP information, if such a procedure exists, and continues the call associated with the parent dialog. The PES interworking application shall release the call if the INFO request fails and there is any ISUP information in the INFO request that requires call release if it cannot be processed or forwarded. 5.3.5.4.2.7.3 Content disposition for other SIP messages A PES interworking application sending an NSS message body in any SIP message other than the INVITE request and the INFO request shall mark it for optional handling. NOTE: A PES interworking application sending an NSS message body in any SIP response message will mark it for optional handling, since the peer SIP signalling entity cannot reject the message. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.4.3 Receiving an NSS message body from a peer SIP signalling entity | 5.3.5.4.3.1 General On receipt of a SIP message containing an NSS message body, the PES interworking application supporting NSS shall de-encapsulate the ISUP information from the NSS message body, perform the processing described in clauses 5.3.5.4.3.2 and 5.3.5.4.3.3, and pass the ISUP information to the relevant ISUP procedures. 5.3.5.4.3.2 ISUP compatibility procedures (local policy options) A PES interworking application shall reject with a SIP 603 (Decline) response a SIP request that includes an NSS message body that is marked for required handling, that includes ISUP information that the PES interworking application does not support, and that requires release according to ISUP procedures when unsupported. Otherwise, the PES interworking application shall ignore any unsupported ISUP information. The PES interworking application may ignore any unsupported ISUP information it receives in an NSS message body marked for optional handling or perform any other behaviour determined by the ISUP procedures. 5.3.5.4.3.3 Alignment of SIP signalling and NSS message body contents On receipt of a SIP message containing an NSS message body, the PES interworking application shall use the encapsulated ISUP information in preference to any value determined by interworking procedures and default values defined in TS 129 163 [32]. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 41 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.4.4 ISUP messages for special consideration | 5.3.5.4.4.1 General Table 3 lists the PES interworking application behaviour upon receipt of ISUP messages that have no counterparts in basic SIP call control messages. Table 3: ISUP messages for special consideration ISUP message Reference Subsequent address message 5.3.5.4.4.6 Reset circuit 5.3.5.4.4.2 Call progress 5.3.5.4.4.3 (see note 1) Circuit group blocking 5.3.5.4.4.2 Circuit group blocking acknowledgement 5.3.5.4.4.2 Circuit group query (national use) 5.3.5.4.4.2 Circuit group query response (national use) 5.3.5.4.4.2 Group reset 5.3.5.4.4.2 Circuit group reset acknowledgement 5.3.5.4.4.2 Confusion 5.3.5.4.4.2 or 5.3.5.4.4.3 (see note 2) Facility reject 5.3.5.4.4.2 or 5.3.5.4.4.3 (see note 2) User-to-user information 5.3.5.4.4.3 Forward transfer 5.3.5.4.4.3 Subsequent directory number (national use) 5.3.5.4.4.3 Suspend 5.3.5.4.4.3 or 5.3.5.4.4.5 Resume 5.3.5.4.4.3 or 5.3.5.4.4.5 Blocking 5.3.5.4.4.2 Blocking acknowledgement 5.3.5.4.4.2 Continuity check request 5.3.5.4.4.2 Continuity 5.3.5.4.4.2 Unblocking 5.3.5.4.4.2 Unblocking acknowledgement 5.3.5.4.4.2 Unequipped CIC (national use) 5.3.5.4.4.2 Circuit group unblocking 5.3.5.4.4.2 Circuit group unblocking acknowledgement 5.3.5.4.4.2 Charging information (national use) 5.3.5.4.4.3 Facility accepted 5.3.5.4.4.3 Facility request 5.3.5.4.4.3 User part test 5.3.5.4.4.2 User part available 5.3.5.4.4.2 Facility 5.3.5.4.4.3 Network resource management 5.3.5.4.4.3 Identification request 5.3.5.4.4.3 Identification response 5.3.5.4.4.3 Information (national use) 5.3.5.4.4.3 Information request (national use) 5.3.5.4.4.3 Segmentation 5.3.5.4.4.4 Loop back acknowledgment (national use) 5.3.5.4.4.3 Loop prevention 5.3.5.4.4.3 Overload (national use) 5.3.5.4.4.2 Pass-along (national use) 5.3.5.4.4.3 Application transport 5.3.5.4.4.2 or 5.3.5.4.4.3 (see note 2) Pre-release information 5.3.5.4.4.3 Release complete 5.3.5.4.4.2 NOTE 1: This is the default handling of the ISUP information associated with the Call Progress (CPG) message when other clauses in the present document do not apply. The ISUP information associated with a CPG message may be encapsulated in an 18X response, an UPDATE request, a reINVITE request, or an INFO request. NOTE 2: The ISUP information in the these messages is either locally terminated or sent transparently depending on whether it is destined for the PES interworking application or for another exchange. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 42 5.3.5.4.4.2 ISUP side procedures only ISUP information from these messages is not encapsulated within SIP messages since they relate to procedures that are relevant only for the ISUP interface. Typically these messages are related to maintenance of ISUP circuits. If ISUP information associated with these ISUP messages is received within an NSS message body, the ISUP information shall be discarded. 5.3.5.4.4.3 Transparent messages If the PES interworking application is configured to forward ISUP information meant for end-to-end service transparency, the PES interworking application shall send the ISUP information through the SIP network as described in clause 5.3.5.4.2.5. 5.3.5.4.4.4 ISUP segmentation ISUP information from the Segmentation message itself is not encapsulated within SIP. Instead the PES interworking application will reassemble the original message received from the PSTN with its segmented part and encapsulate any relevant information in accordance with other procedures in the present document. 5.3.5.4.4.5 Receipt of network initiated SUS and RES If the I-MGCF is not the controlling exchange for network initiated Suspend procedures and NSS message bodies are supported by the peer SIP signalling entity, then the I-MGCF shall forward ISUP information from received SUS and RES in NSS message bodies. If the I-MGCF is the controlling exchange for network initiated Suspend procedures or is unable to forward SUS information to the peer SIP signalling entity, the I-MGCF shall invoke the procedures described in ITU-T Recommendation Q.764 [30], clause 2.4.1c on the ISUP interface and shall not forward ISUP information from either SUS or RES. 5.3.5.4.4.6 Subsequent address message When receiving overlap signalling on the ISUP interface, the PES interworking application shall include the current values of all encapsulated ISUP information in each INVITE request. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.5.5 Optional SIP/ISUP interworking procedures for PSTN Bridging | If the PES interworking application can determine that a call is for PSTN bridging (i.e. that the call will end up in an ISUP network) then the PES interworking application may, as a network option, use the interworking procedures defined in EN 383 001 [20] for Profile C. The way the PES interworking application detects that a call is for PSTN bridging is outside the scope of the present document (local tables or data base lookups may be used). For PSTN bridging, the PES interworking application may route the SIP INVITE request according to the IMS transit mechanism, or any other mechanism, based on local policy. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.6 PES interconnection application | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.6.1 General | In addition to the procedures specified in the rest of clause 5.3.6, the PES interconnection application shall support the procedures specified in TS 124 229 [4] appropriate to an IBCF. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 5.3.6.2 Procedures related to NSS message bodies | Depending on local policy, the PES interconnection application in an IMS PES supporting NSS, acting as a B2BUA, may perform any reasonable combination of the following functions related to an NSS message body within a received SIP message, where the message is to be forwarded either into or outside of the IMS PES: • removal of an Accept header list entry for NSS ("application/nss"); ETSI ETSI TS 183 043 V3.4.1 (2011-04) 43 • removal of an NSS message body marked for optional handling; • filtering of NSS message body parameters (e.g. removal of ISUP information associated with a service not supported by the network); and • rejection of a SIP request that includes an NSS message body marked for required handling by returning a SIP 415 (Unsupported Media Type) response. A PES interconnection application shall only forward NSS message bodies to or from trusted networks supporting NSS. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6 Protocol using SIP/SDP for PES | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.1 Introduction | This clause identifies the functional entities of the IMS-based PES architecture [3] that play a specific role in the provision of PES services with regards to SDP processing in the context of SIP signalling. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.2 Functional Entities | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.2.1 User Equipment (UE) | Conventional SIP UEs do not exist in PES (see clause 5.2.1). For the purpose of the PES, the VGW shall implement the role of a PES endpoint as described in clause 6.3.1. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.2.2 Access Gateway Control Function (AGCF) | For the purpose of the PES, the AGCF shall implement the role of the PES access point as described in clause 6.3.2. The AGCF entity encompasses the functionality of a Media Gateway Controller (MGC) and of a SIP User Agent. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.2.3 Application Server (AS) | For the purpose of the PES, the AS shall implement the role of a PES application server, as described in clause 6.3.3. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.2.4 Media Resource Function Controller (MRFC) | For the purpose of the PES, an MRFC shall implement the role of the PES announcement server as described in clause 6.3.4. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.2.5 Voice over IP gateway (VGW) | For the purpose of the PES, the VGW shall implement the role of the PES end point as described in clause 6.3.1. The VGW entity encompasses the functionality of a Media Gateway Controller (MGC), Media Gateway (MG) and of SIP User Agent. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 44 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3 Roles | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1 PES Endpoint | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.1 General | In addition to the procedures specified in the rest of clause 6.3.1, the PES endpoint shall support the procedures specified in TS 124 229 [4] appropriate to an IMS UE. When sending an SDP payload in a SIP message, the PES endpoint shall not include the "i=", "u=", "e=", "p=", "r=", and "z=" lines in the SDP, and it shall ignore them when received in the SDP. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.2 Originating Calls | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.2.1 Analogue Access | For calls originating from an analogue access, the PES endpoint shall build an SDP offer as follows: see below clauses concerning the negotiation preparation phase. There are multiple combinations of possibly offered media configurations, dependent primarily on locally supported configurations and configuration preferences (see e.g. also annex D in [i.5]). 6.3.1.2.1.1 Supported configuration: "VoIP audio" • The media description shall contain the G711 A-law codec and may contain other audio codecs as well as complementary codecs (e.g. "telephone-event" (see RFC 4733 [17] Comfort Noise (see RFC 3389 [54])) etc.). 6.3.1.2.1.2 Supported configuration: either "V.152 VBDoIP" or "T.38 FoIP" • If the PES endpoint is supporting Voiceband data (V.152 VBDoIP emulation service) or Fax over IP (T.38 FoIP emulation service) the initial session description should contain at least one of the following offers dependent on the network configuration: - preferably (due to its more general nature with respect to PSTN modem calls) an offer for Voiceband Data over IP (VBDoIP) according to V.152 [48]; - in case of knowledge about PSTN G3FE call type: an offer for Fax over IP (FoIP) according to T.38 [49] with the additions specified in annex H of the present document. 6.3.1.2.1.3 Supported configuration: both "V.152 VBDoIP" and "T.38 FoIP" • If the PES endpoint provides support for both V.152 and T.38, the PES endpoint shall build an SDP offer as follows: a) Media configurations for VoIP audio and V.152 VBDoIP: An "m=" line with the media field set to "audio" and a list of codecs including at least one of the G.711 static payload types and a dynamic payload type associated to G.711 VBD. An "a=gmpd" line associating the dynamic payload type to G.711 VBD. b1) Media configuration for T.38 FoIP in case of legacy SDP offer/answer protocol: If the option for support of revised SDP offer/answer model does not apply: - An "m=" line signalling support of T.38 according to the profile defined in clause H.3. - Group the two media descriptions using FID semantics as specified in RFC 3388 [53] (note 1). ETSI ETSI TS 183 043 V3.4.1 (2011-04) 45 NOTE 1: The application of RFC 3388 [53] allows to establish two media configurations (audio and T.38) in parallel, but the usage is conditional (see clause 7.4 in TR 183 072 [i.5]). There are e.g. following limitations: - T.38 transport variants are not negotiable; - other T.38 options (e.g. "T.38 G3" only vs "T.38/V.34 G3") are not negotiable. NOTE 2: When the VGW supports V.34-capable T.38 (in the user plane), then it should support the correspondent indication and negotiation capability (in the control plane too): such a signalling capability in the (T.38) IP domain would be related to T.38 parameter "T38ModemType" in order to discriminate between T.38 modes "T.38/G3" and "T.38/V.34G3". It may be noted that just using the T.38 parameter "T38FaxVersion" in order to discriminate between T.38 modes "T.38/G3" and "T.38/V.34G3" would be not sufficient (see also clause H.3 in T.38 [49]). NOTE 3: T.38 (FoIP-type) specific configurations are e.g. categorized in clause 7.1.2.1 in TR 183 072 [i.5], which provides also guidelines concerning indicated and negotiated T.38 parameters. An "a=pfmt" attribute set to T.38 if this fax relay is preferred to V.152 VBD. NOTE 4: Preferred Configuration (Codec) List (PCL) in SDP offer: This SDP attribute is only required if SDP offer is encoded in legacy SDP Offer/Answer syntax. The indication of preferences is inherent in revised SDP Offer/Answer syntax, related to the numbering of potential configurations (see also clause 7.2.2 in TR 183 072 [i.5]). b2) Media configuration for T.38 FoIP in case of revised SDP offer/answer protocol: If the option for support of revised SDP offer/answer model applies: - An "a=" line explicitly indicating the media capability negotiation according to [50] and [51]. - At least the following "a=sescap" lines for session configuration allowing: - the combination of VoIP (at least for G.711 [23]) and V.152 VBD; - the combination of VoIP (at least for G.711 [23]) and Fax over IP as per T.38 [49]. NOTE 5: The model of session configurations is required due to the need of two parallel media configurations in case of T.38 (see clause D.2.4.2.4 in T.38 [49], or clause 7.4.2.1 in TR 183 072 [i.5]). If T.38 fax relay is preferred to V.152 VBD then according to the preference schema of revised SDP offer/answer model the session capability number associated to T.38 shall be given a lower value than the session capability number associated to V.152 VBD. "a=" lines for the offer of transport and media specific attributes including also T.38 specific attributes. "a=pcfg" lines for potential configurations referenced in "a=sescap" lines. "a=lcfg" lines if latent configurations apply, which are not intended to be established initially but might be already negotiated during the session establishment phase. Same as for potential configurations latent configurations are referenced in "a=sescap" lines. NOTE 6: The model of latent configuration is required for T.38 support due to the fact that all PSTN modem call emulation services starting in voice mode (and not e.g. directly in T.38 mode, see clauses D.2.2.4.3 and D.2.4.2.1 in T.38 [49]). An example for the coding of an offer indicating preferred support of V.152 VBD over support of T.38 can be found in [48] and [52]. 6.3.1.2.1.4 Supported configuration: "V.152 VBDoIP" only, no "T.38 FoIP" • If the PES endpoint provides support for only V.152, the PES endpoint shall build an SDP offer as follows: a) Media configurations for VoIP audio and V.152 VBDoIP: An "m=" line with the media field set to "audio" and a list of codecs including at least one of the G.711 static payload types and a dynamic payload type associated to G.711 VBD. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 46 An "a=gmpd" line associating the dynamic payload type to G.711 VBD. If the option for support of revised SDP offer/answer model applies then in addition: - An "a=" line explicitly indicating the media capability negotiation according to [50] and [51]. - "a=" lines for the offer of transport and media specific attributes. - "a=pcfg" lines for potential configurations to provide the preferred order of VoIP and VBDoIP media configurations. 6.3.1.2.1.5 Supported configuration: "T.38 FoIP" only, no "V.152 VBDoIP" • If the PES endpoint provides support for only T.38, the PES endpoint shall build an SDP offer as follows: a) Media configurations for VoIP audio and non-V.152 VBDoIP: An "m=" line with the media field set to "audio" and a list of codecs including at least one of the G.711 static payload types (due to non-V.152 VBDoIP). b1) Media configuration for T.38 FoIP in case of legacy SDP offer/answer protocol: If the option for support of the revised SDP offer/answer model does not apply: - An "m=" line signalling support of T.38 according to the profile defined in clause H.3. - Group the two media descriptions using FID semantics as specified in RFC 3388 [53]. b2) Media configuration for T.38 FoIP in case of revised SDP offer/answer protocol: If the option for support of the revised SDP offer/answer model applies - An "a=" line explicitly indicating the media capability negotiation according to [50] and [51]. - At least the following "a=sescap" line for session configuration allowing: - the combination of VoIP (at least for G.711) and Fax over IP as per T.38. - "a=" lines for the offer of transport and media specific attributes including also T.38 specific attributes. - "a=pcfg" lines for potential configurations referenced in "a=sescap" lines. - "a=lcfg" lines for potential configurations referenced in "a=sescap" lines. 6.3.1.2.1.6 Supported configuration: neither "V.152 VBDoIP" nor "T.38 FoIP", thus "non-V.152 VBDoIP" • If the PES endpoint provides support for neither V.152 nor T.38, the PES endpoint shall build an SDP offer as follows: a) Media configurations for VoIP audio and non-V.152 VBDoIP: An "m=" line with the media field set to "audio" and a list of codecs including at least one of the G.711 static payload types (due to non-V.152 VBDoIP). 6.3.1.2.1.7 Interworking aspects If the PES endpoint provides support of V.152 and/or T.38, any interworking to equipment not supporting V.152 or T.38, shall be covered by backward compatibility procedures using subsequent offer/answer cycles as specified in clause 6.3.1.4. Annex H gives further details on support of T.38 and V.152. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 47 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.2.2 ISDN Access | For calls originating from an ISDN access, the PES endpoint shall build an SDP offer according to TS 183 036 [40]. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.3 Terminating Calls | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.3.1 General | When the PES endpoint sends a SIP Response Code 183 (Session Progress) with SDP payload, it shall only request confirmation for the result of the resource reservation at the originating endpoint if there are any remaining unfulfilled preconditions. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.3.2 Analogue Access | The PES endpoint shall: • reject any media descriptions whose media type is different from "m=audio" or "m=image", by setting the corresponding port to 0; • in case of "m=image" for support of Fax over IP in addition the proper subtype stating T.38 shall be verified; • check for codecs that match the requested SDP. When the PES endpoint generates and sends a SIP Response Code 183 (Session Progress) to an initial SIP INVITE request, the PES endpoint shall: • set the SDP media description (as SDP answer) indicating the selected audio codec(s) and complimentary codecs received in the SDP offer; • include a VBD codec as per ITU-Recommendation V.152 if supported by this endpoint and included in the received SDP offer. If ITU-T Recommendation T.38 [49] is supported by this endpoint and is included in the received SDP, then the SDP answer should include a "m=image" line (and T.38 SDP attributes, see also note) indicating support of T.38 as described in clause H.3. NOTE: T.38 (FoIP-type) specific configurations are e.g. categorized in clause 7.1.2.1 in TR 183 072 [i.5], which provides also guidelines concerning indicated and negotiated T.38 parameters. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.3.3 ISDN Access | Processing of media description for calls terminating on an ISDN access shall conform to TS 183 036 [40]. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.4 Specific procedures for PSTN modem calls | The Offer/Answer exchange previously described results in a Negotiated Codec List (NCL) for the session. For VBD, the key point is whether one or both of V.152 and T.38 is included in the NCL. The order of media configurations in the NCL reflects the preferred configurations of both the Offerer and Answerer (e.g. the Offerer did indicate his PCL in the sent OCL; see e.g. also annex D in [i.5]). If there is support for both V.152 and T.38 in the NCL, then dependent on the configuration preferences, e.g. fax/modem may be transmitted via T.38 (fax relay) or V.152 and other non fax/modem traffic may be transmitted via V.152 (VBDoIP emulation service). Otherwise, if there is no support for both V.152 and T.38, then fallback procedures are necessary - see clause 6.3.1.4.3. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.4.1 Generation of Preferred Configuration/Codec Lists (for PSTN modem calls) | The notion of "fax/modem calls" implies multiple media configurations (e.g. for audio, voiceband data or packet relay mechanism) indicated and negotiated. TR 183 072 [i.5] provide guidelines for the generation of Preferred Configuration/Codec Lists (PCL) for PSTN modem calls. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 48 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.4.2 Switching between "audio" and "non-audio" modes | Procedures for switch over from audio mode to fax/modem calls are described in clause H.2 (for voiceband data mode) and clause H.3 (for fax relay mode). |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.4.3 Fall Back due to lacking support of V.152 and/or T.38 | In the following the basic scenarios for fall back are described: • If the NCL contains neither V.152 nor T.38 then a fall back to pseudo-VBD (G.711, voiceband data merged with audio mode) shall apply. • If the NCL contains T.38 and not V.152, then fax data shall be transmitted via T.38 shall happen for PSTN G3FE calls, and a fallback to pseudo-VBD for all other non-fax modem call types shall happen. NOTE: There might be different fallback procedures with regards to T.38 modes "T.38/G3" and "T.38/V.34G3". This related to the explicit signalling of T.38 parameter "T38ModemType". If the NCL contains V.152 and not T.38, then, all VBD traffic shall be transmitted via V.152. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.1.4.4 Non-V.152 VBD Gateway | A non-V.152 VBD gateway lacks support of V.152 SDP information elements, i.e. lacking support of RTP PT assignments of dynamic range for "VBD codec". However, such gateways may provide some basic support VBD calls if the following capabilities would be implemented: • the ability to detect VBD stimuli; • the control of echo cancellers (EC) as per ITU-T Recommendation G.168 [55] (taking into account the operational relation of ECs and VBD according clause 6.2 of V.152); • the disabling Voice Activity Detection and Comfort Noise Generation if any of these had been activated; • ensuring end-to-end constant latency; • ensuring that voice packet loss concealment techniques and algorithms that may be employed are suitable for modem and facsimile modulations; and • the disabling any DC removal filters that may be integral with the speech encoder used. Non-V.152 VBD Gateways reuse the Audio G.711 media formats "PCMU" and "PCMA" with its "RTP/AVP" profile (RFC 3551 [i.7]) specific static RTP payload value assignments for VBD purpose ("a merged audio/VBD mode"). Each end transitions independently to non-V.152 VBD mode based only on local VBD stimuli detection. The non-V.152 VBD Gateway uses only static payload types 0 (PCMU) or 8 (PCMA) according to "RTP/AVP" profile (RFC 3551 [i.7]) for VBD. The following rules shall be applied in order select PCMA or PCMU for the VBD codec at start of call: • If the negotiated codec list (NCL) includes a single PCM format, use the correspondent static PCM RTP payload type for the VBD codec. If the NCL includes both PMCU and PCMA, the highest priority G.711 codec is used for VBD. • If the NCL does not include G.711, upon VBD stimuli detection the VGW should send a SIP Re-INVITE with a new SDP OFFER containing only the supported G.711 static payload type(s). Upon successful negotiation of a G.711 static payload type in the SDP ANSWER, that same payload type shall be re-used as the VBD codec. Note that if G.711 is not contained in the SDP ANSWER, then the VGW shall initiate appropriate exception handling (e.g. release the call). Such exception handling is out of scope of the present document. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 49 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2 PES Access Point | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.1 General | In addition to the procedures specified in the rest of clause 6.3.2, the PES access point shall support the procedures specified in TS 124 229 [4] appropriate to an AGCF. When sending an SDP, the PES access point shall not include the "i=", "u=", "e=", "p=", "r=", and "z=" lines in the SDP, and it shall ignore them when received in the SDP. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.2 Originating calls | The PES access point shall follow the procedures described in clause 6.3.1.2 Originating Calls for the PES endpoint. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.3 Terminating calls | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.3.1 General | When the PES access point sends a 183 (Session Progress) response with SDP payload, it shall only request confirmation for the result of the resource reservation at the originating endpoint if there are any remaining unfulfilled preconditions. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.3.2 Analogue Access | The PES access point shall follow the procedures described in clause 6.3.1.3.2 Analogue Access for the PES endpoint. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.3.3 ISDN Access | Processing of media description for calls terminating on an ISDN access shall conform to TS 183 036 [40]. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.4 Void | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.2.5 Specific Procedures for Fax/Modem Calls | The procedures between the AGCF and AGW are described in clause 6.2 of TS 183 002 [5]. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.3 PES Application Server | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.3.1 General | In addition to the procedures specified in the rest of clause 6.3.3, the PES application server shall support the procedures specified in TS 124 229 [4] appropriate to an application server. When acting as a B2BUA, the PES application server must appropriately handle SDP received in responses received from a forking Proxy and must appropriately interwork SDP received in provisional and final INVITE responses, as well as other SIP requests, between the originating UA and terminating UA functions employed on a single call. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.4 PES Announcement Server | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.4.1 General | In addition to the procedures specified in clause 6.3.4, the PES announcement server shall support the procedures specified in TS 124 229 [4] appropriate to an MRFC. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 50 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 6.3.5 SDP support for PSTN modem calls | Clauses 6.3.1 and 6.3.2 define SDP capabilities, required for the emulation of PSTN modem calls by the IMS domain. These SDP capabilities are primarily subject of 3GPP specifications, resulting in a dependency of the present document to some 3GPP specifications. Status - end of 2010: Existing 3GPP Release 9 specifications for TS 124 229 [4] and TS 129 163 [32] still lacking support of SDP attributes for T.38 and V.152, which prevents the indication and negotiation of correspondent media configurations. NOTE: Lacking support of SDP attributes for T.38 and V.152 by 3GPP specifications TS 124 229 [4] and TS 129 163 [32] allows just a limited support of emulation services for PSTN modem calls as defined in clauses 6.3.1 and 6.3.2 in the present document (see also [i.5]). The TISPAN R3 defined solution does in this respect not provide any added value in comparison to pre-R3 releases. Annex I provides an indication on possible impact on IMS-based PES network deployments. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7 Protocol using H.248 for PES | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.1 Introduction | This clause identifies the functional entities of the IMS-based PES architecture [3] that play a specific role in the provision of PES services with regards to H.248 processing. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.2 Functional Entities | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.2.1 Access Gateway Control Function (AGCF) | For the purpose of the PES, the AGCF shall implement the role of the PES access point as described in clause 7.3.1. The AGCF entity encompasses the functionality of an H.248 Media Gateway Controller (MGC) and of a SIP User Agent. Within the AGCF, the MGC and SIP UA components are coordinated by a Feature Manager entity whose logical behaviour is described in annex B. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.2.2 Media Gateway Function (MGF) | For the purpose of the PES, the MGF shall implement the role of the PES media gateway as described in clause 7.3.2. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3 Roles | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1 PES Access Point | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.1 General | In addition to the procedures specified in the rest of clause 7.3.1, the PES access point shall support the procedures specified in TS 183 002 [5] appropriate to an MGC. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.2 Registration | Registration is supported using the H.248 Service Change procedure. Registration can be performed on a group basis or on a per line/access basis. This event is passed to the Feature Manager. NOTE: A group may consist of all lines connected to a PES media gateway or to a subset of the media gateway. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 51 When the group basis registration mechanism applies, on receipt of a ServiceChange command with "Root" TerminationID from the PES media gateway reporting the MGW state changing event and after processing the event according to normal service change procedures has finished, the MGC in the PES access point shall send a Service-Change primitive to inform the Feature Manager if the ServiceChangeMethod is set to "Restart" with ServiceChangeReasons 901 ("Cold Boot") or 902 ("Warm Boot") or "Forced" or "Graceful". Receipt of a ServiceChange command from the PES media gateway reporting a Terminations state changing event shall not cause the MGC in the PES access point to notify the Feature Manager. When the per line basis registration mechanism applies, on receipt of a ServiceChange command from the PES media gateway, and after processing the event according to normal service change procedures has finished, the MGC in the PES access point shall send a Service-Change primitive to inform the Feature Manager if the ServiceChangeMethod is set to "Restart" with ServiceChangeReasons 900 ("Service Restored") or 902 ("Warm Boot") or "Forced" or "Graceful". When the MGC in the PES access point detects that the PES media gateway lost communication with the MGC in the PES access point, but it was subsequently restored, since MGW state may have changed, the MGC in the PES access point may use the H.248 Audit mechanism to resynchronize its state with the PES media gateways. If the MGC in the PES access point detects that the audited state of the specified Terminations is different from the recorded state, the MGC in the PES access point shall use a Service-Change primitive with proper parameters to inform the Feature Manager about the event. When the MGC in the PES access point detects that the PES media gateway lost the communication with the PES media gateway, the MGC in the PES access point shall use Service-Change primitive with proper parameters to inform the Feature Manager about this event. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.3 Basic Session control procedures for analogue lines | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.3.1 Originating side procedures | 7.3.1.3.1.1 Call Initiation Step 0 (IDLE) On receipt of a Notify command from the PES media gateway reporting the off-hook (al/of) event the PES access point shall: • Derive the user identity associated with the termination reporting the event. • Report the occurrence of the off-hook event to the Feature Manager using a Session-Attempt primitive. • If the subscriber profile (see annex A) contains a no-dialling-behaviour = immediateCallSetup indication, - request the PES media gateway to create an H.248 context with the caller's analogue termination and an ephemeral termination; - send a Setup Request primitive to the Feature Manager without digits, SDP information shall be set according to the information received in the Reply to the H.248 Add command used to create the ephemeral termination; - request the PES media gateway to detect and report al/on event, and - proceed to step 2, waiting for either al/on or an event from the Feature Manager. • Otherwise interact with the Feature Manager to determine which dial tone pattern shall be applied (see clause 5.3.2.2). • Request the PES media gateway to apply the signal that correspond to the selected dial tone (cg/dt or srvt/mwt or xcg/spec) according to the value of the dial-tone-pattern element of the Dial Tone Management document described in annex A. • Request the PES media gateway to detect and report al/on event. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 52 NOTE 1: The PES media gateway terminations may also be preconfigured by the PES access point, using signals and events descriptors embedded in the al/of event descriptor, in such a way that upon detection of the off-hook event, the dial tone is automatically delivered and the digit collection is automatically started. The PES access point replaces the event descriptors in case the dial tone is modified. • Request the PES media gateway to detect and report the xdd/xce event, according to the digit map in force and proceed with step 1. Step 1 (Outgoing Seizure – prior sending of digits) On receipt of the al/on event, the PES access point shall send a Session-Release-Request primitive to the Feature Manager and complete call clearing procedures as specified in clause 7.3.1.3.1.2. On receipt of the notification of the xdd/xce event, the PES access point shall: • If the received digits do not correspond to a valid number but receipt of additional digits may lead to a valid number, request the PES media gateway to detect and report the following events: - the xdd/xce event, according to a subsequent digit map; - the al/on event. This step may be repeated several times, until a valid number has been collected or the user has abandoned the call attempt by going back on-hook. • If the received digits do not correspond to a valid number and receipt of additional digits cannot lead to a valid number: - initiate call clearing. • If the received digits correspond to a complete number, the PES access point shall: - request the PES media gateway to create an H.248 context with the caller's analogue termination and an ephemeral termination; - send a Setup-Request primitive to the Feature Manager. SDP information shall be set according to the information received in the Reply to the Add command; - request the PES media gateway to detect and report the following events: 1) the al/fl event; 2) the al/on event. - wait for either of these events and for events from the Feature Manager. Proceed to step 2 on the occurrence of any of these events. • If no digits are received with the xdd/xce event, the PES access point shall initiate call clearing during off- hook (clause 7.3.1.3.1.3) unless the subscriber profile (see annex A) contains a no-dialling-behaviour = deferredCallSetup indication. In the latter case the PES access point shall: - request the PES media gateway to create an H.248 context with the caller's analogue termination and an ephemeral termination; - request the PES media gateway to detect and report the al/on event; - send a Setup Request primitive to the Feature Manager without digits, SDP information shall be set according to the information received in the Reply to the H.248 Add command used to create the ephemeral termination; - wait for either the al/on event or an event from the Feature Manager. Proceed to step 2 on the occurrence of any of these events. Step 2 (Outgoing Seizure – after sending of digits) On receipt of the notification of the al/on event, the PES access point shall send a Session-Release-Request primitive to the Feature Manager and complete call clearing procedures as per clause 7.3.1.3.1.2. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 53 On receipt of the notification of the al/fl event, the PES access point shall notify its Feature Manager using a Feature Request primitive. On receipt of a Session Progress primitive from the Feature Manager without alerting indication, the PES access point shall: • If the primitive contains an early media indication resulting from the presence of a P-Early-Media header field in the associated SIP response, request the PES media gateway to modify the ephemeral termination properties accordingly so that the calling party can perceive in band information. NOTE 2: The termination mode may be set to send-receive or receive-only depending on the network operator's policy. • If the primitive does not contain an early media indication, ignore the event. • Remain in the same state. On receipt of a Session Progress primitive from the Feature Manager indicating alerting, the PES access point shall: • If the primitive contains an early media indication resulting from the presence of a P-Early-Media header field in the associated SIP response, request the PES media gateway to modify the ephemeral termination properties accordingly so that the calling party can perceive in band information. NOTE 3: The termination mode may be set to send-receive or receive-only depending on the network operator's policy. • If the primitive does not contain an early media indication, request the PES media gateway to apply the cg/rt signal to the physical termination. • Proceed with step 3. On receipt of a Setup-Response primitive reporting a busy condition, the PES access point shall: • Initiate call clearing during off-hook procedure (clause 7.3.1.3.1.3). NOTE 4: In this case the PES media gateway to apply the cg/bt signal to the physical termination at the start of the call clearing. On receipt of an internal Setup-Response primitive reporting that no response has been received from the destination, the PES access point shall: • Initiate Call Clearing during off-hook procedure (clause 7.3.1.3.1.3). • If required by local policy, request the PES media gateway to apply a signal (e.g. cg/ct) to the physical termination depending on the type of failure. On receipt of an internal Setup-Response primitive reporting any other failure condition, the PES access point shall: • Initiate Call Clearing during off-hook procedure (clause 9.3.1.3.1.3). On receipt of a Setup-Response primitive reporting answer from the destination, the PES access point shall: • Request the PES media gateway to set the mode of the termination to send-receive. • Modify the ephemeral termination's remote descriptor properties in accordance with SDP information received from the remote side, if any. • As an operator's option request the PES media gateway to apply the xal/las signal. • Proceed with step 4. Step 3 (Outgoing Seizure – provisional response received) On receipt of the al/on event, the PES access point shall send a Session-Release-Request primitive to the Feature Manager and complete call clearing procedures as specified in clause 7.3.1.3.1.2. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 54 On receipt of the notification of the al/fl event, the PES access point shall notify the feature manager using a Feature Request primitive. On receipt of a Setup-Response primitive reporting that no response has been received from the destination or any other failure, the PES access point shall: • Request the PES media gateway to stop the ring back (cg/rt) signal if application of this signal had been requested before. • Send a Session-Release-Request primitive to the Feature Manager and complete Call Clearing procedures as specified in clause 7.3.1.3.2.1. On receipt of a Setup-Response primitive reporting answer from the destination, the PES access point shall • Request the PES media gateway to set the mode of the ephemeral termination to send-receive if not performed previously. • Modify the ephemeral termination's remote descriptor properties in accordance with SDP information received from the remote side, if any. • As an operator's option request the PES media gateway to apply the xal/las signal. • Proceed with step 4. Step 4 (Outgoing Session established) On receipt of a Session-Release-Request primitive from the Feature Manager, the PES access point shall initiate the call clearing during off-hook procedure (clause 9.3.1.3.1.3). On receipt of a Charging-Indication primitive, depending on operator policy the PES access point shall either: • Generate metering pulses by rules described in clause C.2 and request the PES media gateway to apply one of the signals for sending metering pulses (amet/em or amet/mpb or amet/phsm) defined in ITU-T Recommendation H.248.26 [14]. • Build an Advice Of Charge message (see ES 200 659-3 [10]) by rules described in annex D and request the media gateway to transmit this message, using the Generic Data Signalling (data) signal of the Analog Display Signalling (andisp) package defined in ITU-T Recommendation H.248.23 [13]. On receipt of a Session-Update primitive, the PES access point shall modify the ephemeral termination properties accordingly. On receipt of the al/on event, the PES access point shall send a Session-Release-Request primitive to the Feature Manager and complete call clearing procedures as specified in clause 7.3.1.3.1.2. On receipt of the notification of the al/fl event, the PES access point shall notify the feature manager using a Feature Request primitive. 7.3.1.3.1.2 Call Clearing upon On-Hook On receipt of a Session-Release-Confirm primitive from the Feature Manager the PES access point shall: • As a network option request the PES media gateway to apply the xal/nd signal. • Request the PES media gateway to subtract the ephemeral termination from the current context. • Request the PES media gateway to move the termination back to the Null context (i.e. subtract command). NOTE: The PES media gateway applies Normal Polarity (i.e. if a Reversed Polarity has been applied to the line at start of call, it is removed upon termination going back to Null context). • Proceed with step 0. On receipt of a Session-Release-Suspend primitive from the Feature Manager the PES access point shall request the MGW to monitor the al/of event. If the al/of event is detected, the PES access point shall send a Session-Resume primitive to the Feature Manager and re-enter Step 4 of the previous phase. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 55 7.3.1.3.1.3 Call Clearing during Off-Hook Upon entering this step, the PES access point shall: • Request the PES media gateway to generate an appropriate announcement or tone on the subscriber line. • As a network option, upon end of announcement or tone, request the PES media gateway to apply the xal/nd signal. • Request the PES media gateway to subtract the ephemeral termination from the current context. On receipt of the al/on event, the PES access point shall: • Request the PES media gateway to move the termination back to the Null context (i.e. subtract command). • if a Session Release-Request primitive has been previously received from the Feature Manager, send a Session-Release-Confirm to the Feature Manager. • Proceed with step 0. If the calling party is still off-hook upon end of announcement or tone, the PES access point shall, after expiry of a network configured timer, request the PES media gateway to apply the off-hook warning tone (xcg/roh) to the physical termination. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.3.2 Terminating side procedures | 7.3.1.3.2.1 Call Initiation Step 0 (Idle) On receipt of a Setup-Request primitive from the internal SIP UA (via the Feature Manager), the PES access point shall: • Check that the required bearer service is compatible with analogue lines, otherwise return a Setup-Response to the Feature Manager, with a reject indication. • Determine which physical termination(s) are associated with the target public user identity. • If no termination is associated with the called party, the PES access point shall send a Setup-Response primitive with a failure indication to the internal SIP UA via the Feature Manager. If a single termination is associated to the target public user identity, select this termination otherwise if multiple terminations are associated to the target public user identity, select one termination. • Check the administrative status of the selected termination. If the termination is out of service, the PES access point shall send a setup-response primitive with a failure indication to the internal SIP UA via the Feature Manager or select another termination if multiple terminations are associated to the called number. If all terminations are out of service, the PES access point shall send a Setup Response primitive with a failure indication to the internal SIP UA via the Feature Manager. • Check whether the selected termination is already engaged in a call. NOTE 1: As an operator's option, an AuditValue command may be sent to the Media Gateway to verify the status of the termination. NOTE 2: The algorithm for selecting a termination in case multiple terminations are associated to the same public user identity (fixed priority, round-robin, etc.) is outside the scope of the present document. NOTE 3: It is expected that only one termination will be associated to a public user identity when the tight-coupling mode is used. If the selected termination is not engaged in a call, the PES access point shall: • Create an H.248 context with an ephemeral termination, based on the session description information received in the Setup-Request. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 56 • Add the physical termination representing the called party's line to the newly created context. • Request the PES media gateway to apply ringing to the physical termination using the andisp/dwa signal. The Display Data Block parameter of the andisp/dwa signal shall be set as specified in annex D. As directed by the AS (with a SIP Alert-Info header in the INVITE request), the PES access point may direct the PES media gateway to apply a distinctive ringing tone by setting the pattern parameter to the appropriate value. NOTE 4: The alert/ring signal may be used in place of the andisp/dwa signal in networks where presentation of call information to the called party is not supported. • Send a Session-Progress (Alerting) primitive to the Feature Manager. • Start a no-answer timer. • Request the PES media gateway to detect the off-hook event (al/of). • Proceed to step 1. If the selected termination is already engaged in a call and multiple terminations are associated to the same called number, select an alternative termination and repeat the above procedures. If the selected termination is already engaged in a call and there is no alternative "in-service" termination that can be selected, the PES access point shall either: • Send a Setup-Response (busy) primitive to the Feature Manager if an explicit indication that the Call Waiting service is not provisioned to the user has been received as part of the profile delivery procedure or as a network option if the incoming Setup-Request does not contain a MIME body indicating that the terminating user is subscribed to the Call Waiting service as defined in TS 124 615 [44]; or • Initiate a call waiting procedure: - Create an H.248 context with an ephemeral termination, based on the session description information received in the Setup-Request. - Request the PES media gateway to apply the call waiting tone to the physical termination using the andisp/dwa signal. The Display Data Block parameter of the andisp/dwa signal shall be set as specified in annex D. As directed by the AS (with a SIP Alert-Info header in the INVITE request), the PES access point may direct the PES media gateway to apply a distinctive call waiting tone by setting the pattern parameter to the appropriate value. NOTE 5: The cg/cw signal may be used in place of the andisp/dwa signal in networks where presentation of call information to the called party is not supported. - Send a Session-Progress (Alerting) primitive to the Feature Manager, including 'urn:alert:service:call-waiting' to be inserted in the Alert-Info header field of the corresponding SIP message. - Start a call-waiting timer. - Proceed to step 1. If a Session-Release-Request primitive is received from the feature manager (resulting from receipt of a CANCEL request by the internal UA), the PES access point shall: • Request the PES media gateway to subtract the ephemeral termination. • Request the PES media gateway to move the physical termination back to the Null context. • Send a Session-Release-Confirm primitive to the Feature Manager. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 57 Step 1 (Incoming Seizure) If an off-hook (al/of) event is notified, the PES access point shall: • Request the PES media gateway to detect the following events: - the al/fl event; - the al/on event. • Report the occurrence of the off-hook event to the Feature Manager using a Setup-Response (answer) primitive. • Proceed to step 2. If the no-answer timer (line free) or call-waiting-timer (line busy) expires, the PES access point shall: • send a Setup-Response (no answer) primitive to the internal UA via the Feature Manager. • Request the PES media gateway to stop the signal sent to the called party (ringing or call waiting signal). • Request the PES media gateway to stop the signal sent to the calling party (ring back tone or the announcement). • Move the physical termination representing the called party's line back to the NULL context, unless this termination is already engaged in another call. • Send a Session-Release-Request primitive to the Feature Manager and complete call clearing procedures as specified in clause 7.3.1.3.2.2. Step 2 (Incoming Session established) If the al/fl event is received from the PES media gateway, notify the Feature Manager using a Feature Request primitive. On receipt of a Session-Update primitive, the PES access point shall modify the ephemeral termination properties accordingly. If the al/on event is received from the PES media gateway, the PES access point shall send a Session-Release-Request primitive to the Feature Manager and complete call clearing procedures as per clause 7.3.1.3.2.2. If a Session-Release-Request primitive is received via the Feature Manager from the internal UA, the PES access point shall initiate call clearing during off-hook procedure (clause 7.3.1.3.2.3). 7.3.1.3.2.2 Call Clearing upon On-Hook On receipt of a Session-Release-Confirm primitive from the Feature Manager the PES access point shall: • Request the PES media gateway to subtract the ephemeral termination. • Request the PES media gateway to move the physical termination back to the Null context. • Proceed with step 0. On receipt of a Session-Release-Suspend primitive from the Feature Manager the PES access point shall request the MGW to monitor the al/of event. If the al/of event is detected, the PES access point shall send a Session-Resume primitive to the Feature Manager and re-enter Step 2 of the previous phase. 7.3.1.3.2.3 Call Clearing during Off-Hook Upon entering this step, the PES Access Point shall: • Request the PES media gateway to subtract the ephemeral termination. • Request the PES media gateway to apply an appropriate announcement or tone (e.g. busy tone, congestion tone etc.) to the physical termination. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 58 On receipt of the al/on event, the PES Access point shall: • Request the PES media gateway to move the physical termination back to the Null context. • Report the occurrence of the on-hook event to the Feature Manager using a Session-Release-Confirm primitive if a Session-Release-Request had been received. • Proceed with step 0. If the line is still off-hook at the end of the announcement/tone, request the PES media gateway to apply the off-hook warning tone (xcg/roh) to the physical termination after expiry of a network configured timer. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.4 Procedures for fax/modems calls over analogue access | In order to be able to properly handle fax and modem calls, the PES access point requests the media gateway to monitor the ctyp/dtone event. On receipt of a notification of the ctyp/dtone event, the AGCF notifies the Feature Manager if the recognized tone corresponds to a supported fax/modem. Otherwise, the event is discarded. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.5 Message Waiting Indication for analogue access | On receipt of a Service Notification primitive reporting the "message-summary" event, the PES access point shall request the media gateway to apply the Generic Data Signalling signal of the andisp package defined in ITU-T Recommendation H.248.23 [13]. The value of the TAS parameter is provisioned in the media gateway or in the PES access point, per media gateway or per line. Annex D specifies the populating rules for the Data Block parameter of the Generic Data Signalling signal. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.1.6 Procedures for ISDN access | FFS. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 7.3.2 PES Media Gateway | The PES media gateway shall support the H.248 procedures specified in TS 183 002 [5] appropriate to an MG. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8 Protocol using DSS1 for PES | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.1 Introduction | This clause identifies the functional entities of the IMS-based PES architecture [3] that play a specific role in the provision of PES services with regards to DSS.1 processing. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.2 Functional Entities | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.2.1 User Equipment (UE) | Conventional SIP UEs do not exist in PES (see clause 5.2.1). For the purpose of the PES, the VGW shall implement the role of a PES endpoint as described in clause 8.3.1. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.2.2 Access Gateway Control Function (AGCF) | For the purpose of the PES, the AGCF shall implement the role of the PES access point as described in clause 8.3.2. The AGCF entity encompasses the functionality of a Media Gateway Controller (MGC) and of a SIP User Agent. ETSI ETSI TS 183 043 V3.4.1 (2011-04) 59 |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.2.3 Signalling Gateway Function (SGF) | For the purpose of the PES, the SGF shall implement the role of the PES signalling gateway as described in clause 8.3.3. NOTE: For the purpose of relaying call control signalling (SAPI=0), the SGF is co-located with an MGF. As a network option, an SGF may also be co-located with the VGW for relaying p-type and f-type frames (SAPI=16 or SAPI between 32 and 62). |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.2.4 Voice over IP gateway (VGW) | For the purpose of the PES, the VGW shall implement the role of the PES endpoint as described in clause 8.3.1. The VGW entity encompasses the functionality of a Media Gateway Controller (MGC), Media Gateway (MG) and a SIP User Agent. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.3 Roles | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.3.1 PES Endpoint | The PES Endpoint shall support the DSS1 protocol according to EN 300 403-1 [41]. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.3.2 PES Access Point | The PES Access point shall support the DSS1 protocol according to EN 300 403-1 [41] and one or more backhaul procedures described in TS 183 002 [5] for relaying ISDN D-channel information, depending on the type of ISDN access supported. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 8.3.3 PES Signalling Gateway | The PES signalling gateway shall support one or more backhaul procedures described in TS 183 002 [5] for relaying ISDN D-channel information, depending on the type of ISDN services supported. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 9 Protocol using analog signalling for PES | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 9.1 Introduction | This clause identifies the functional entities of the IMS-based PES architecture [3] that play a specific role in the provision of PES services with regards to analog signalling processing. |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 9.2 Functional Entities | |
f35b69ccd2199c2dc10834594190c0f0 | 183 043 | 9.2.1 User Equipment (UE) | Conventional SIP UEs do not exist in PES (see clause 5.2.1). |
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