Nortel Networks Remote Gateway 50 - Manual (Page 228)

Page 228 of 258 Emergency Services configuration
553-3001-207 Standard 2.00 January 2006
The implications of routing calls to nodes without direct ESA trunks are as
follows:
• At the node without the direct ESA trunks, the node cannot route the ESA
call directly to the PSAP. Instead, that node must re-route the call to
another node. This re-routing is an unnecessary use of resources.
• If the node is a CS 1000E node, the only tandem trunks are IP Peer
trunks. There is no way to specify the appropriate rerouting digits (that
is, Prepend Digits) to reroute the ESA call to another node with direct
ESA trunks.
Therefore, if unable to route ESA calls directly to the PSAP, the next best
practice is to route ESA calls to nodes with direct ESA trunks.
Routing configuration for ESA calls on SRG50
Use the following steps to configure routing for ESA calls for the SRG50:
1 Build a destination code corresponding to the ESA SPN for the branch
office.
2 Configure the destination code to absorb the leading digits for the SPN,
leaving just the ESPN.
3 Configure the destination code to use a public route to the PSTN trunks.
4 Ensure the Remote access package (00 to 15 under Call Security)
assigned to the VoIP trunks has the appropriate Line Pool Access/Bloc
for PRI.
5 Ensure there is a Public Prefix of 911 with a length of 3 to match to
outgoing digits. This eliminates any delay. As soon as the 3 digits are
collected, the call is sent.
Configuring ESA for the branch office
For ESA, the main office Call Server forwards the call to the branch office for
termination. Calls are redirected over a Virtual Trunk using the NRS services.
The NRS routes the calls using a special number, referred to in this section as
the ESA Special Number.