Nortel BCM 3.7, Manual

Page: 525 / 1004

Creating tandem private networks 525
Programming Operations Guide
In this type of network, you must ensure that each Business Communications Manager system,
known as a node of the network, is set up to route calls internally as well as to other nodes on the
system. This means, each node must have a route to the immediately-adjacent node, and the
correct codes to distribute the called numbers. Each node must have a unique identification
number, which is determined by the type of dialing plan chosen for the network.
As well, you can save costs by having a public network connection to only one or two nodes, and
routing external calls from other nodes out through the local PSTN, thus avoiding toll charges for
single calls.
This section includes the following:
• “Calls originating from the public network” on page 525
• “Calls originating in the private network” on page 528
• “Routing for tandem networks” on page 530
VoIP note: You can also use VoIP trunks between some or all of the nodes. The setup is the same,
except that you need to create gateway records for each end of the trunk, and routing tables to
accommodate the gateway codes. Refer to the
IP Telephony Configuration Guide for information
about setting up VoIP trunks and gateway programming.
Calls originating from the public network
The following table describes who each node handles calls originated from the public network into
the system.
Table 115 Call originating from the public network to a tandem network
Received Destination Description
Node A Node A User in Calgary dials 761-xxxx number
Incoming interface: Public
DN type: Public
Node A receives the call and identifies it as terminating locally. Uses target line to route
call (Public received #).
Destination: Local (target line)
Node A Node B User in Calgary dials a 762-xxxx number
DN type: Public
Node A receives it and identifies it as being for node B. Uses private trunk to route it to B.
Incoming interface: Public
Destination: Remote Node
Outgoing interface: Private
Node B receives the call and identifies it as terminating locally. Uses target line to route
call (Private received #).
Incoming interface: Private
Destination: Local (target line)