Network Requirements and Preparation
Planning and Installation Guide
9 – 29
ShoreTel 6.1 automatically negotiates the proper voice encoder at call setup. For calls
between sites, the call control software requests the voice encoder based on what is
selected for inter-site voice encoding as defined on the Call Control Options edit page.
The call control software will then make sure both endpoints on the call can support
the requested voice encoder.
For instance, for G.729a voice encoding to be used between two sites, the inter-site
voice encoding must be set to G.729a and the ShoreGear voice switches at each end of
the call must be G.729a-capable.
WAN Bandwidth per Call (Full Duplex) Without cRTP
Table 9-14 defines the bandwidth, including IP overhead, that is used for each voice
call between sites when RTP Header Compression (cRTP) is not being used. The
bandwidth depends on the voice encoding used. For example:
•
If you want to support 10 calls between this site and all other sites, and G.729a
voice encoding is used, set the admission control bandwidth to 260 Kbps. Before
you enter this value, make sure the bandwidth is available at this site.
•
If you set your admission control bandwidth to 768 Kbps and G.729a voice
encoding is used, you can support up to 29 calls between this site and all other
sites.
NOTE
ShoreTel recommends that you configure the admission control bandwidth to be
less than the bandwidth of the actual WAN link. This provides sufficient
bandwidth for call control signaling and other data traffic.
Table 9-14 Bandwidth Without cRTP
Bandwidth in
Kbps per
Number of Calls
Linear
G.711
ADPCM
G.729a
1
146
82
52
26
2
292
170
104
52
3
438
255
156
78
4
584
340
208
104
5
730
425
260
130
6
876
510
312
156
7
1022
595
364
182
8
1168
680
416
208
9
1314
765
468
234
10
1460
850
520
260
11
1606
935
572
286
12
1752
1020
624
312
13
1898
1105
676
338
14
2044
1190
728
364
15
2190
1275
780
390
16
2336
1360
832
416
17
2482
1445
884
442
18
2628
1530
936
468
19
2774
1615
988
494
20
2920
1700
1040
520
