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Feature Reference
Emergency 911 calls
Administrator’s Guide for Avaya Communication Manager 1527
November 2003
Emergency Extension Forwarding
If an emergency call should drop (get disconnected), the public safety personnel will attempt to call back.
If the ELIN that was sent was not equivalent to the caller’s extension number, the return call would ring
some other set than the one that dialed 911. To overcome that limitation, you can automatically forward
that return call to the set that placed the emergency call for an administered period of time.
The Emergency Extension Forwarding (min) field on the Feature-Related System Parameters screen
allows you to set the Emergency Extension Forwarding timer for all incoming trunk calls if an emergency
call gets cut off (drops).
This Emergency Extension Forwarding only applies if the emergency location extension number is an
extension on the same PBX as the extension that dialed 911. Customers who have several PBXs in a
campus should assign emergency location extensions accordingly.
Interactions
Duplication Interactions
NOTE:
The following two scenarios are written from the point of view of a Local Spare Processor
(LSP), but also apply to backup S8700 servers. The same interaction also happens if the
spare processor is an ATM WAN spare processor, or is on a Survivable Remote EPN.
Sending the correct ELIN to the PSAP
The LSP copies administration translations from its primary server once a day. Translations are never
copied from the LSP to the primary server. Currently, IP telephones can stay under the control of an LSP
for either 6 days
or 10 days, or forever. The length of time depends on which load of software the
customer is running.
If you are notified after an IP extension moves, update the ALI database with the extension’s physical
location. You should also change the
Emergency Location Extension
field to match the extension’s new
IP subnet. Then, if the telephone registers with the LSP before the next copying of translations from the
main to the LSP, the
Emergency Location Extension
field in the loaded translations would still be set to
the old value. If the user dials 911, emergency response personnel would go to the user’s approximate
location instead of the exact location.
You should not update translations on the LSP; the reverse situation should never occur.
Call Forwarding dropped emergency calls
Suppose that an IP telephone and a nearby Media Gateway that provides a connection to the PSTN are
both registered to a primary server. Suppose that the gateway is backed up by an LSP, and that the IP
telephone has some LSPs in its alternate gatekeeper list. Suppose that the IP telephone dials 911, and then
the LAN crashes and partially recovers. If both the IP telephone and the Media Gateway can re-register to
the primary server, everything is fine. If both the IP telephone and the Media Gateway are forced to
register with the same LSP, everything is fine.
But if one of them re-registers to one LSP and the other re-registers to the primary server, or if they
re-register to different LSPs, there’s a minor problem. When the emergency response personnel call back,
the server that the Media Gateway is registered with will think that the IP telephone is unregistered. The
Media Gateway’s server will not be able to forward the call to the IP telephone. Instead, the Media
Gateway’s server will attempt to ring the call at the telephone equivalent to the sent ELIN.