Alternative Call Routing for Network Bandwidth Management Page 137 of 258
3The 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.
4The 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.
5The virtual trunk places the call to the branch office.
6The 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 page 134).
Example: Refer to Figure 43 on page 136.
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 page 141.
7Call comes into IP Phone A from the PSTN or MCDN trunks in the main office zone (action labeled 3 in Figure 42 on page 134).
Main Office Configuration for Survivable Remote Gateway 50 Configuration Guide
