Page 138 of 258 Alternative Call Routing for Network Bandwidth Management
A call from a main office telephone to a branch office telephone
Figure 44 shows two CS 1000 systems. The system shown on the left is a main office. The system shown on the right is a branch office. Both systems have access to the PSTN. The Wide Area Network (WAN) is shown in the center with a gatekeeper/Network Routing Service (NRS) that can be co-resident with a Signaling Server. IP Phones are also shown associated with each system. Telephone A belongs to the main office. Telephone B is a telephone at the branch office registered to the main office. There are two bandwidth zones indicated by the dashed line (main office zone [MO zone] and branch office zone [BO2 zone]). Telephone A and the Media Gateway belong to the MO zone. Telephones B and C and the branch office belong to the BO2 zone.
Figure 44
Example of an alternately routed call between a main office telephone and a branch office telephone
Telephone A calls Telephone B (the user dials DN 3121). In this example, the call alternately routes to the PSTN. (The PSTN telephone number of Telephone B is
