Emergency services 173
The key differencebetween the main office user and the Branch User is the
route selected for the emergency call. An emergency call must be handed
off to the PSTN over a trunk at the central office that is geographically
closest to the caller — this means that there is normally an emergency trunk
in the main office, and one in each of the branch offices. An emergency call
originating from an MG 1000B IP Phone must route from the main office
Call Server to the MG 1000B CP PM so that the call can be sent on the
MG 1000B PSTN.
ATTENTION
IMPORTANT!
In Normal Mode, an IP Phone must havea Vir tual Trunkavailable and configured
between the main office and Branch Office to complete an emergency services
call.
ATTENTION
IMPORTANT!
Do not route ESA calls to a node that has no direct ESA trunks.
Refer to "Routing ESA calls" (page 316) for more information on routing
ESN calls.
There are two general methods to specify which digit string results in a
call to emergency services:
•Use 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. ESA provides specific features and capabilities required by
legislation in these jurisdictions.
•Use a special dialing sequence, such as a Special Number (SPN) in the
Network Alternate Route Selection (NARS) data block.
Refer to "Emergency Services configuration" (page 315) for more
information on ESA and SPN configuration.
Configuring ESA for emergency services
The ESA configuration specifies the digit sequence (a DN) that the user
dials to start an emergency call, known as the 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.
If the Branch Office and the main office do not use the same digits for
emergency calls, it is not possible to use ESA at both locations. Refer to
Emergency Services Access Fundamentals (NN43001-613) for complete
information.
Nortel Communication Server 1000
Branch Office Installation and Commissioning
NN43001-314 01.02 Standard
Release 5.0 20June 2007
Copyright© 2007, Nor tel Networks
.