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Helpful Tip:ANI Failures

Anonymous Callso Definition- Anonymous calls occur when someone calls a PSAP

directly using the 911 trunk number. The PSAP does not receive avalid ANI with an anonymous call. The bid is identified in the ALI logas an ALI retrieval on TN 911-0000.

o Additional information In the early 90s when Wireless was justgetting started, dialable 9-1-1 trunk numbers were often given toWireless Service Providers (WSP) to facilitate forwarding wirelesscalls into the PSAP on traditional 9-1-1 trunks. This was a great ideaat the time, but now this method circumvents the selective routingprocess and does not pass the call back number. These bids need tobe analyzed as a pattern, one or two calls a months can simply be

misdials, but in significant numbers they indicate a problem.o What to do Look for a Wireless Service Provider with a tower/face

that has not been converted to Phase I/II, or a tower/face that hasreverted back to Phase 0. Turn in a ticket to your tandem provider.Ask your Wireless Service Providers to retest if necessary.

ESCO Failureso Definition- When a bid cannot be selectively routed, the bid is routed

based on the ESCO code of the central office where it originated.Each ESCO is designated an ESN, which is the basis for this sort ofdefault emergency call routing. The bid is identified in the ALI log as an

ALI retrieval on TN 911-0xxx, where xxx represents the ESCOgenerating the call.

o Additional information ESCO failures can either be wire line orwireless, but they are always associated with ANI failures from theoriginating end office. They are tandem specific and every tandem iscapable of having the same ESCO numbers representing differentcentral offices. These failures should be analyzed by tandem lookingfor patterns. In significant numbers they indicate a problem.

o What to do Ask your tandem provider to identify which central officeis failing using the ESCO. If it is wireless, refer the issue to theappropriate Wireless Service Provider. If it is wire line, have the PSAP

open a trouble ticket with the tandem provider.

Seizure Bidso Definition- Seizure bids occur when there is an ANI failure between

the Tandem / Selective Router and PSAP. The bid is identified in theALI Log as an ALI retrieval on TN 000-0000.

o Additional information When the tandem has a call to send to aPSAP, it signals the PSAP equipment by putting a seizure (short) on

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the line. The trunk unit at the PSAP responds by reversing the polarity(wink) to show it is ready. If the trunk unit at the PSAP perceives aseizure, it will wink and then after a period of time launch an ALI bidwith the ANI it has received. If the seizure was not valid, the ANI bidwill be all zeros. These seizures often show up in bad weather and are

an indication of line trouble. They can even fix themselves when theline dries out. Other possibilities are they can be a sign of trouble at thePSAP trunk unit or the tandem trunk unit. These bids need to beanalyzed as a pattern; one or two calls a day can simply be hits on theline, but in significant numbers they indicate a problem.

o What to do Have the PSAP open a trouble ticket with the tandemprovider and the CPE provider.

Seizure

failure

000-000-0000

End Serving

Central Office

(ESCO) failure

000-911-0XXX or

NPA-911-0XXX

Anonymous call

failure

000-911-0000

Tandem COCentral Office

Mobile Switching

Center

9-1-

9-1-1

Tandem

trunk side

Central Office

line side

Dialable trunk

Dialable trunk

ANI

ANI

ANI

Public Switched

Telephone

dedicated trunkdedicated

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