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5.5.3 DSP Resource Usage
•
Accessing the Unified Messaging system (including recording calls)
•
OGM playback
•
Echo canceller (for trunk-to-trunk analogue calls)
For IP extension and trunk calls, the number of required resources differs depending on the codec (G.711 or
G.729) used.
Note
The examples in this section are intended to illustrate the concept of DSP resource usage. More
complex situations may necessitate additional resources, and in some cases fewer resources may be
necessary.
Examples of DSP resource usage
Fundamentally, the number of resources required for a given situation is the sum of the resources required
for each individual operation. The following examples illustrate DSP resource usage in various situations.
[IP trunk to IP extension]
IP Trunk
If an IP trunk call using the G.729 codec requires X number of resources, and an IP extension call using the
G.711 codec requires Y number of resources, then the number of resources required for a call from an IP
extension to an IP trunk requires X + Y number of resources.
[Unified Messaging access]
X
UM
G.711
PBX
Playing back messages from or recording messages to the Unified Messaging (UM in the figure above)
system requires DSP resources, X in this example, in addition to the resources required for the G.711 codec
(Y). The total cost is X + Y.
[Conference call]
IP Trunk
IP Trunk
416
Feature Manual
Y
X
PBX
G.711
G.729A
Y
IP-PT
X
G.711
X
Y
G.711
Conference
X
G.711
X
G.711
PBX
IP-PT
W
G.729A
IP-PT
Z
Analogue
SLT
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