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Two-way Recording also requires a conference trunk. For an example of the required DSP resources, see 5.5.3 DSP Resource
*2
Usage.
Example 1: Small Office
In a small office (e.g., 32 employees), the necessary number of trunks and extensions is likely to be
relatively small. In addition, the expected load on the system will also be small.
(For clarity, unused services are not included in the table.)
Service
Trunk using G.729 codec
Non-IP trunk
Extension using G.729 codec
Unified Messaging
OGM
Conference
DSP Cost = Number of Ports × Resource cost per port (unit) × Load
*1
In the example above, the total DSP cost is 18.55. In such an environment, a PBX with a DSP S card (max.
63 DSP resources) would be sufficient.
Example 2: Call Centre
In a call centre, both the number of trunks and number of extensions are likely to be very high. Also, since
employees are constantly receiving calls, the system load will be high. Furthermore, calls are often recorded
at call centres to provide quality-of-service monitoring.
Service
Trunk using G.729 codec
Trunk using G.711 codec
Extension using G.729 codec
Extension using G.711 codec
IP-CS using G.729 codec
Unified Messaging
Two-way Recording
OGM
Conference
DSP Cost = Number of Ports × Resource cost per port (unit) × Load
*1
In this example, the total DSP cost is 291.2. In this case, two DSP cards are necessary: at minimum one
DSP L card (max. 254 DSP resources) and one DSP S card (max. 63 DSP resources).
Conditions
•
Calls that are established via P2P (→ 5.2.3 Peer-to-Peer (P2P) Connection) do not use the PBX's DSP
resources, so they may be excluded from the usage calculation.
Number of Ports
Load (Busy Ratio %)
3
1
32
4
2
4
Number of Ports
Load (Busy Ratio %)
8
128
32
128
8
8
4
4
12
5.5.3 DSP Resource Usage
5%
5%
10%
—
—
—
Total DSP Cost
50%
80%
50%
80%
50%
—
—
—
—
Total DSP Cost
Feature Manual
DSP Cost
*1
0.3
0.05
7.0
5.2
4.0
2.0
18.55
DSP Cost
*1
8.8
102.4
35.2
102.4
8.8
10.4
9.2
8.0
6.0
291.2
421
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