Avaya Communication Manager, Руководство администратора, Страница: 1526 / 1854

Feature Reference
Emergency 911 calls
1526 Administrator’s Guide for Avaya Communication Manager
November 2003
A caller who needs emergency assistance dials a Universal Emergency Number — for example, 911 in
the United States, 000 in Australia, and 112 in the European community. The call routes through a local
Central Office, through an emergency tandem office, to the appropriate Public Safety Answer Point
(PSAP). The PSAP answers the call.
A typical tandem office can route the call to a PSAP within at most four surrounding areas. (In the US,
that translates to four surrounding area codes.) If the PSAP that receives the call is not the correct one to
handle the emergency, the PSAP might be able to transfer the call to the correct PSAP. Such transfers can
only occur between geographically adjacent or nearby PSAPs.
Each PSAP usually covers one city or one rural county. At the PSAP, emergency operators determine the
nature of the emergency and contact the appropriate agency: police, fire, ambulance, etc. A single PSAP
is usually responsible for an area covering several independent police and fire departments in the United
States.
With Enhanced 911 (E911), the system might send to the emergency services network the Calling Party
Number (CPN) with the call over Centralized Automatic Message Accounting (CAMA) trunks or
through the Calling Number IE over ISDN trunks. A mux at the PSAP uses the CPN to lookup the
caller’s documented street address location from the Automatic Location Information (ALI) database.
The ALI database is usually owned and managed by Local Exchange Carriers. Many enterprise
customers choose to contract with a third party to update the ALI database for them.
This depends on the assumption that a CPN always corresponds to the street address that the system
owner arranged to have administered into the ALI database. This assumption is not always true.
•
Users who have H.323 IP telephones can move them without notifying the system administrator.
•
Users who have SIP IP telephones can use the same extension number simultaneously at several
different telephones.
With this feature, the emergency response personnel can go to the correct physical location. In addition,
emergency response personnel can go to the correct physical location if a 911 emergency call comes from
a bridged call appearance.
Whenever an IP station dials an emergency call, Communication Manager compares the Emergency
Location Extension field administered on the
IP Address Mapping screen for that station’s IP address
with the Emergency Location Ext field administered on the Station screen.
•
If the two are the same, the telephone most likely has not moved, or at most moved within the
same subnet.
•
If the two are different and the emergency location extension administered on the IP Address
Mapping screen is non-blank, then the telephone has moved from one subnet to another.
•
If the emergency location extension administered on the IP Address Mapping screen is blank,
then the administrator expected the caller to be located outside the LAN. Most likely that is true
for a softphone.
CAUTION:
Whenever an administrator adds an extension as an Emergency Location Extension to the
IP Address Mapping screen (use the ip-network-map command), the administrator
should check all of the station forms for stations in that ip address range.
If the station is a DID number, the administrator should make sure that the
Station form
has the same Emergency Location Extension as does the IP Address Mapping form.
If the station is not a DID number, the administrator should make sure that the Station
screen has a different
Emergency Location Extension than does the IP Address
Mapping screen.