phrack/issue24/6.txt

                                ==Phrack Inc.==

                      Volume Two, Issue 24, File 6 of 13

         [][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
         []                                                        []
         []                  Glossary Terminology                  []
         []                For Enhanced 911 Services               []
         []                                                        []
         []                   By The Eavesdropper                  []
         []                                                        []
         []                       March, 1988                      []
         []                                                        []
         [][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]


E911 - Enhanced 911:  Features available include selective routing, selective
       transfer, fixed transfer, alternate routing, default routing, Automatic
       Number Display, Automatic Location Identification, night service,
       default routing, call detail record.

End Office - Telephone central office which provides dial tone to the
             subscriber calling 911.  The "end office" provides ANI (Automatic
             Number Identification) to the tandem office.

Tandem Office - Telephone central office which serves as a tandem (or hub) for
                all 911 calls.  Must be a 1AESS type of central office.  The
                tandem office translations contain the TN/ESN relationships
                which route the 911 call to the proper SAP.  The tandem office
                looks up the ANI (TN) that it receives from the end office and
                finds the ESN (routing information) which corresponds to a
                seven digit number ringing in at a PSAP.

PSAP - Public Safety Answering Point, usually the police, fire and/or rescue
       groups as determined by the local municipalities.  A "ringin" will not
       have ANI or ALI capabilities, but just receives calls or transferred
       calls from another PSAP.

ESN - Emergency Service Number (XXX) that is assigned to the subscriber's
      telephone number in the tandem office translations The ESN represents a
      seven digit number by which the tandem office routes the call to the
      proper PSAP.  PSAPs with ALI capabilities also receive a display of the
      ESN information which shows which police, fire and rescue agency serves
      the telephone number calling 911.  An ESN is a unique combination of
      police, fire, and rescue service for purposes of routing the E911 call.

ANI - Automatic Number Identification corresponds to the subscriber's seven
      digit telephone number.  The ANI displays at the PSAP on the digital ANI
      display console.

ALI - Automatic Location Identification provides for an address display of the
      subscriber calling 911.  With ALI, the PSAP receives the ANI display and
      an ALI display on a screen.  The ALI display includes the subscriber's
      address, community, state, type of service and if a business, the name of
      the business.  The PSAP will also get a display of the associated ESN
      information (police, fire, rescue).

Selective Routing - The capability to route a call to the particular PSAP
                    serving the address associated with the TN making the 911
                    call.  Selective routing is achieved by building TN/ESN
                    translations in the tandem central office.  These
                    translations are driven by the E911 data base which assigns
                    the ESN to each telephone number based on the customer's
                    address.  Service order activity keeps the E911 data base
                    updated.  The E911 data base, in turn, generates recent
                    change to the tandem office (through the SCC or RCMAC) to
                    update the TN/ESN translations in the tandem data base.

Selective Transfer - Provides the PSAP with the ability to transfer the
                     incoming 911 call to a fire or rescue service for the
                     particular number calling 911 by pushing one button for
                     fire or rescue.  For example, if an incoming 911 call was
                     reporting a fire, the PSAP operator would push the fire
                     button on the ANI console; the call would go back to the
                     tandem office, do a lookup for the seven digit number
                     associated with fire department, for the ESN assigned to
                     the calling TN, and automatically route the call to that
                     fire department.  This differs from "fixed" transfer which
                     routes every call to the same fire or rescue number
                     whenever the fire or rescue button is pushed.  The PSAP
                     equipment is optioned to provide either fixed or selective
                     transfer capabilities.

Alternate Routing - Alternate routing provides for a predetermined routing for
                    911 calls when the tandem office is unable to route the
                    calls over the 911 trunks for a particular PSAP due to
                    troubles or all trunks busy.

Default Routing - Provides for routing of 911 calls when there is an ANI
                  failure.  The call will be routed to the "default" ESN
                  associated with the he NNX the caller is calling from.
                  Default ESNs are preassigned in translations and are usually
                  the predominant ESN for a given wire center.

Night Service - Night service works the same as alternate routing in that the
                calls coming into a given PSAP will automatically be routed to
                another preset PSAP when all trunks are made busy due to the
                PSAP closing down for the night.

Call Detail Record - When the 911 call is terminated by the PSAP operator, the
                     ANI will automatically print-out on the teletypewriter
                     located at the PSAP.  The printout will contain the time
                     the call came into the PSAP, the time it was picked up by
                     an operator, the operator number, the time the call was
                     transferred, if applicable, the time the call was
                     terminated and the trunk group number associated with the
                     call.  Printouts of the ALI display are now also
                     available, if the PSAP has purchased the required
                     equipment.

ANI Failure - Failure of the end office to identify the call and provide the
              ANI (telephone number) to the tandem office; or, an ANI failure
              between the tandem office and the PSAP.

Misroute - Any condition that results in the 911 call going to the wrong PSAP.
           A call can be misrouted if the ESN and associated routing
           information are incorrect in the E911 data base and/or tandem data
           base.  A call can also be misrouted if the call is an ANI failure,
           which automatically default routes.

Anonymous Call - If a subscriber misdials and dials the seven digit number
                 associated with the PSAP position, they will come in direct
                 and ANI display as 911-0000 which will ALI as an anonymous
                 call.  The seven digit numbers associated with the PSAP
                 positions are not published even to the PSAPs.

Spurious 911 Call - Occasionally, the PSAP will get a call that is not
                    associated with a subscriber dialing 911 for an emergency.
                    It could be a subscriber who has not dialed 911, but is
                    dialing another number, or has just picked up their phone
                    and was connected with the PSAP.  These problems are
                    equipment related, particularly when the calls originate
                    from electromechanical or step by step offices, and are
                    reported by the E911 Center to Network Operations upon
                    receipt of the PSAP inquiry reporting the trouble.  The
                    PSAP may get a call and no one is there; if they call the
                    number back, the number may be disconnected or no one home.
                    Again these are network troubles and must be investigated.
                    Cordless telephones can also generate "spurious" calls in
                    to the PSAPs.  Generally, the PSAP will hear conversation
                    on the line, but the subscribers are not calling 911.  The
                    PSAP may report spurious calls to to repair if they become
                    bothersome, for example, the same number ringing in
                    continually.

No Displays - A condition where the PSAP ALI display screen is blank.  This
              type of trouble should be reported immediately to the SSC/MAC.
              If all screens at the PSAP are blank, it is an indication that
              the problem is in the circuits from the PSAP to the E911
              computer.  If more than one PSAP is experiencing no display, it
              may be a problem with the Node computer or the E911 computer.
              The SSC/MAC should contact the MMOC to determine the health of
              the HOST computer.

Record Not Found - If the host computer is unable to do a look up on a given
                   ANI request from the PSAP, it will forward a Record Not
                   Found message to the PSA ALI screen.  This is caused by
                   service order activity for a given subscriber not being
                   processed into the E911 data base, or HOST computer system
                   problems whereby the record cannot be accessed at that point
                   in time.

No ANI - This condition means the PSAP received a call, but no telephone number
         displayed on the ANI console.  The PSAP should report this condition
         immediately to the SSC/MAC.

PSAP Not Receiving Calls - If a PSAP cannot receive calls or request retrievals
                           from the E911 host computer, i.e., cable cut, the
                           calls into that PSAP must be rerouted to another
                           PSAP.  The Switching Control Center must be notified
                           to reroute the calls in the tandem office E911
                           translations.

MSAG - Master Street Address Guide.  The MSAG ledgers are controlled by the
       municipality which has purchased the E911 ALI service, in that they
       assign which police, fire or rescue agency will serve a given street and
       number range.  They do this by assigning an ESN to each street range,
       odd, even, community that is populated in the county or municipality
       served.  These MSAGs are then used as a filter for service order
       activity into the E911 computer data base to assign ESNs to individual
       TN records.  This insures that each customer will be routed to the
       correct agency for their particular address.  In a non-ALI County, TAR
       codes are used by the Telephone company to assign ESNs to service
       conductivity and the County does not control the ESN assignment.  TAR
       codes represent the taxing authority for the given subscriber which
       should correspond to their police, fire and rescue agencies.  The MG
       method, of course, is more accurate because it is using the actual
       service address of the customer to route the call and provides the
       county with more flexibility in assigning fire and rescue district, etc.
       The Customer Services E911 Group maintains the E911 computer data base
       and interfaces with the County (customer) on all MSAG or data base
       activity.
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