Configuring Phone Lines and Calling Routing Behavior
Configuring Line Interfaces on the SPA9000
SPA9000 Voice System Administration Guide
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Bandwidth Requirements and Call Capacity
The available connection bandwidth determines the maximum number of
simultaneous calls that the system can support with the appropriate audio quality.
Before installing and configuring the Cisco SPA components, use this information
to determine the maximum number of simultaneous VoIP connections that the
system can support. For asymmetric connections, such as ADSL, the maximum
number of calls is determined by the upstream bandwidth. In general it is a good
practice to use no more than 75% of the total available bandwidth for calls. This
provides space for data traffic and helps ensure good voice quality.
The following table provides the approximate bandwidth budget for different
codecs.
Table 1 Bandwidth Budgeting
Codec
Approximate bandwidth budget (kbps)
Each side of
conversation
2 calls
4 calls
6 calls
8 calls
G.711
110
220
440
660
880
G.726-40
87
174
348
522
696
G.726-32
79
158
316
474
632
G.726-24
71
142
284
426
568
G.726-16
63
126
252
378
504
G.729
55
110
220
330
440
