Nortel Networks Remote Gateway 50 User Manual
Page 137
Alternative Call Routing for Network Bandwidth Management
Page 137 of 258
Main Office Configuration for Survivable Remote Gateway 50
Configuration Guide
3
The Call Server inserts the ALTPrefix configured for the BO2 zone prior
to IP Phone A’s telephone number, dialed by the user.
Example: ALTPrefix assigned is 222. The dialed number becomes
222 5262.
4
The call is routed to the virtual trunk by CDP or VNR. The virtual trunk
sends a request to the NRS for address resolution. The digit string sent to
the NRS
contains the ALTPrefix. The NRS returns the IP address of the
branch office endpoint to the virtual trunk.
5
The virtual trunk
places the call to the branch office.
6
The branch office receives the call and recognizes the first part of the
number as a Steering Code. The call is steered to an RLI. The DMI
manipulates the number into a PSTN number and the branch office
outpulses the digits to the Central Office (CO) serving the branch office.
(This may be the same CO as the one serving the main office.) If the
alternate route has MCDN trunks in the BO2 zone, the call is outpulsed
on one of these trunks, after the branch office uses Digit Manipulation
(action labeled 2 in Figure 42 on
).
Example: Refer to Figure 43 on
2225 is programmed as a Steering Code at the branch office. Calls
starting with this Steering Code are handled by an RLI with a PSTN
trunk route as an entry. If the Public format number for the destination
telephone is a DID number, then the Digit Manipulation Index associated
with the PSTN route must:
— delete 3 digits (remove the ALTPrefix 222)
— insert 1613966 (in order to compose the DID number of the
destination telephone, which is 16139665262)
Note: Program other Steering Codes to route calls to other locations
properly (for example, program Steering Code 2226 to route calls to
another branch office where 15063486XXX would have to be
outpulsed). Refer to the section called “A call from a branch office
telephone to another branch office telephone” on
.
7
Call comes into IP Phone A from the PSTN or MCDN trunks in the main
office zone (action labeled 3 in Figure 42 on