Nortel Networks SRG 50 NN43001-307 - Manual (Page 190)

190 Emergency Services configuration
Nortel recommends using the Emergency Services Access (ESA) feature.
This is the preferred method in North America, the Caribbean and Latin
America (CALA), and in those countries that are members of the European
Union (EU). ESA provides specific features and capabilities required by
legislation in these jurisdictions.
The ESA feature provides the following advantages:
• recognizes special Emergency Service Directory Number (ESDN)
• overrides calling restrictions
• provides optional assignment of ESA CLID per DN
• provides optional selection of a special emergency route
• provides optional routing digits (for NRS resolution)
• provides optional assignment of an Emergency Location Identification
Number (ELIN)
• provides On Site Notification (OSN) through an external tool, which traps
the emergency call event and records an alarm when an emergency
calls are placed at the branch office.
For more information about ESA, see Emergency Services Access
Fundamentals (NN43001-613).
The main office Call Server forwards emergency services calls to the SRG
using a virtual trunk.
Emergency Services Access
The Emergency Services Access (ESA) configuration specifies the digit
sequence (a DN) that the user dials to start an emergency call, known as
the Emergency Services Directory Number (ESDN). There can only be one
ESA configuration per customer and thus only one ESDN per customer,
which means that all telephones on the same network must be in the same
numbering plan.
With all sites using the same ESDN, a conflict occurs in the NRS because
the same ESDN may need to route to different gateways. The conflict is
resolved by using a routing digit for each site that the main office adds as it
routes the call. The suggested routing digit is the ESN home location code
of the SRG, or alternately, the Numbering Plan Area (NPA) code of the SRG
if there is not more than one Call Server in the NPA. Virtually any unique
digit string (maximum 15 digits) can be used as a routing digit, because the
call is sent to the NRS as a Private/Special Number (SPN). In the NRS,
SPN have their own separate numbering plan.
Nortel Communication Server 1000
Main Office Configuration Guide for SRG 50
NN43001-307 02.02 Standard
Release 5.0 3 December 2007
Copyright © 2005-2007, Nortel Networks
.