Specifications

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