PBX Networking Configuration
13.3.1 Trunk groups
This is a group of lines of the same type and direction. A line can only be assigned to one trunk group (bundle).
Network operator
PBX 1 PBX 3
A
B
C
D
E
PBX 2
Bundle
Trunk line
Point-to-point connection
Example of a PBX network with trunk groups
In the above example, the following trunk groups are configured for PBX 1:
■ Two S
0
lines in a multi-terminal configuration to the network operator which are assigned to the “A” trunk group.
■ Two S
0
point-to-point connections to PBX 2 which are assigned to the “C” trunk group.
■ One S
0
point-to-point connection to PBX 3 which is assigned to the “E” trunk group.
Note: A line or a trunk group cannot be seized directly. It is always performed indirectly via a route.
13.3.2 Routes
A route is a group of trunk groups enabling a connection in one direction. If the first trunk group of a route is fully utilized, the next trunk group is seized (“trunk group overflow”). One trunk group can also be used for different routes.
In the above example, a route set up for PBX 1 allows a connection to PBX 2. Trunk groups “C,” “E” and “A” are assigned to this route. If a user connected to PBX 1 wants to reach a party in PBX 2, lines will be seized in the following order:
■ PBX 1 first searches for a free channel in the “C” trunk group.
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