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Nortel Networks Remote Gateway 50 User Manual

Page 138

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Page 138 of 258

Alternative Call Routing for Network Bandwidth Management

553-3001-207 Standard 2.00 January 2006

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 613-966-3121.)