194 lines
12 KiB
Plaintext
194 lines
12 KiB
Plaintext
==Phrack Inc.==
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Volume Two, Issue 24, File 6 of 13
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[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
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[] []
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[] Glossary Terminology []
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[] For Enhanced 911 Services []
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[] []
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[] By The Eavesdropper []
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[] []
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[] March, 1988 []
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[] []
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[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]
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E911 - Enhanced 911: Features available include selective routing, selective
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transfer, fixed transfer, alternate routing, default routing, Automatic
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Number Display, Automatic Location Identification, night service,
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default routing, call detail record.
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End Office - Telephone central office which provides dial tone to the
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subscriber calling 911. The "end office" provides ANI (Automatic
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Number Identification) to the tandem office.
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Tandem Office - Telephone central office which serves as a tandem (or hub) for
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all 911 calls. Must be a 1AESS type of central office. The
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tandem office translations contain the TN/ESN relationships
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which route the 911 call to the proper SAP. The tandem office
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looks up the ANI (TN) that it receives from the end office and
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finds the ESN (routing information) which corresponds to a
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seven digit number ringing in at a PSAP.
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PSAP - Public Safety Answering Point, usually the police, fire and/or rescue
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groups as determined by the local municipalities. A "ringin" will not
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have ANI or ALI capabilities, but just receives calls or transferred
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calls from another PSAP.
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ESN - Emergency Service Number (XXX) that is assigned to the subscriber's
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telephone number in the tandem office translations The ESN represents a
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seven digit number by which the tandem office routes the call to the
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proper PSAP. PSAPs with ALI capabilities also receive a display of the
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ESN information which shows which police, fire and rescue agency serves
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the telephone number calling 911. An ESN is a unique combination of
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police, fire, and rescue service for purposes of routing the E911 call.
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ANI - Automatic Number Identification corresponds to the subscriber's seven
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digit telephone number. The ANI displays at the PSAP on the digital ANI
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display console.
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ALI - Automatic Location Identification provides for an address display of the
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subscriber calling 911. With ALI, the PSAP receives the ANI display and
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an ALI display on a screen. The ALI display includes the subscriber's
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address, community, state, type of service and if a business, the name of
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the business. The PSAP will also get a display of the associated ESN
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information (police, fire, rescue).
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Selective Routing - The capability to route a call to the particular PSAP
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serving the address associated with the TN making the 911
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call. Selective routing is achieved by building TN/ESN
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translations in the tandem central office. These
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translations are driven by the E911 data base which assigns
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the ESN to each telephone number based on the customer's
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address. Service order activity keeps the E911 data base
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updated. The E911 data base, in turn, generates recent
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change to the tandem office (through the SCC or RCMAC) to
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update the TN/ESN translations in the tandem data base.
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Selective Transfer - Provides the PSAP with the ability to transfer the
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incoming 911 call to a fire or rescue service for the
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particular number calling 911 by pushing one button for
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fire or rescue. For example, if an incoming 911 call was
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reporting a fire, the PSAP operator would push the fire
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button on the ANI console; the call would go back to the
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tandem office, do a lookup for the seven digit number
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associated with fire department, for the ESN assigned to
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the calling TN, and automatically route the call to that
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fire department. This differs from "fixed" transfer which
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routes every call to the same fire or rescue number
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whenever the fire or rescue button is pushed. The PSAP
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equipment is optioned to provide either fixed or selective
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transfer capabilities.
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Alternate Routing - Alternate routing provides for a predetermined routing for
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911 calls when the tandem office is unable to route the
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calls over the 911 trunks for a particular PSAP due to
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troubles or all trunks busy.
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Default Routing - Provides for routing of 911 calls when there is an ANI
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failure. The call will be routed to the "default" ESN
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associated with the he NNX the caller is calling from.
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Default ESNs are preassigned in translations and are usually
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the predominant ESN for a given wire center.
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Night Service - Night service works the same as alternate routing in that the
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calls coming into a given PSAP will automatically be routed to
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another preset PSAP when all trunks are made busy due to the
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PSAP closing down for the night.
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Call Detail Record - When the 911 call is terminated by the PSAP operator, the
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ANI will automatically print-out on the teletypewriter
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located at the PSAP. The printout will contain the time
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the call came into the PSAP, the time it was picked up by
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an operator, the operator number, the time the call was
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transferred, if applicable, the time the call was
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terminated and the trunk group number associated with the
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call. Printouts of the ALI display are now also
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available, if the PSAP has purchased the required
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equipment.
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ANI Failure - Failure of the end office to identify the call and provide the
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ANI (telephone number) to the tandem office; or, an ANI failure
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between the tandem office and the PSAP.
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Misroute - Any condition that results in the 911 call going to the wrong PSAP.
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A call can be misrouted if the ESN and associated routing
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information are incorrect in the E911 data base and/or tandem data
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base. A call can also be misrouted if the call is an ANI failure,
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which automatically default routes.
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Anonymous Call - If a subscriber misdials and dials the seven digit number
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associated with the PSAP position, they will come in direct
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and ANI display as 911-0000 which will ALI as an anonymous
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call. The seven digit numbers associated with the PSAP
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positions are not published even to the PSAPs.
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Spurious 911 Call - Occasionally, the PSAP will get a call that is not
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associated with a subscriber dialing 911 for an emergency.
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It could be a subscriber who has not dialed 911, but is
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dialing another number, or has just picked up their phone
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and was connected with the PSAP. These problems are
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equipment related, particularly when the calls originate
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from electromechanical or step by step offices, and are
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reported by the E911 Center to Network Operations upon
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receipt of the PSAP inquiry reporting the trouble. The
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PSAP may get a call and no one is there; if they call the
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number back, the number may be disconnected or no one home.
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Again these are network troubles and must be investigated.
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Cordless telephones can also generate "spurious" calls in
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to the PSAPs. Generally, the PSAP will hear conversation
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on the line, but the subscribers are not calling 911. The
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PSAP may report spurious calls to to repair if they become
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bothersome, for example, the same number ringing in
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continually.
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No Displays - A condition where the PSAP ALI display screen is blank. This
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type of trouble should be reported immediately to the SSC/MAC.
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If all screens at the PSAP are blank, it is an indication that
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the problem is in the circuits from the PSAP to the E911
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computer. If more than one PSAP is experiencing no display, it
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may be a problem with the Node computer or the E911 computer.
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The SSC/MAC should contact the MMOC to determine the health of
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the HOST computer.
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Record Not Found - If the host computer is unable to do a look up on a given
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ANI request from the PSAP, it will forward a Record Not
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Found message to the PSA ALI screen. This is caused by
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service order activity for a given subscriber not being
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processed into the E911 data base, or HOST computer system
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problems whereby the record cannot be accessed at that point
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in time.
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No ANI - This condition means the PSAP received a call, but no telephone number
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displayed on the ANI console. The PSAP should report this condition
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immediately to the SSC/MAC.
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PSAP Not Receiving Calls - If a PSAP cannot receive calls or request retrievals
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from the E911 host computer, i.e., cable cut, the
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calls into that PSAP must be rerouted to another
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PSAP. The Switching Control Center must be notified
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to reroute the calls in the tandem office E911
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translations.
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MSAG - Master Street Address Guide. The MSAG ledgers are controlled by the
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municipality which has purchased the E911 ALI service, in that they
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assign which police, fire or rescue agency will serve a given street and
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number range. They do this by assigning an ESN to each street range,
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odd, even, community that is populated in the county or municipality
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served. These MSAGs are then used as a filter for service order
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activity into the E911 computer data base to assign ESNs to individual
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TN records. This insures that each customer will be routed to the
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correct agency for their particular address. In a non-ALI County, TAR
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codes are used by the Telephone company to assign ESNs to service
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conductivity and the County does not control the ESN assignment. TAR
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codes represent the taxing authority for the given subscriber which
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should correspond to their police, fire and rescue agencies. The MG
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method, of course, is more accurate because it is using the actual
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service address of the customer to route the call and provides the
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county with more flexibility in assigning fire and rescue district, etc.
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The Customer Services E911 Group maintains the E911 computer data base
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and interfaces with the County (customer) on all MSAG or data base
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activity.
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_______________________________________________________________________________
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