Installation guide

52 Planning and Installation Guide ShoreTel 14.2
Network Requirements and Preparation WAN Technology Choices
3
WAN Technology Choices
Minimum Bandwidth Requirements
The minimum WAN bandwidth required to deploy a voice switch at a site depends on the number of
calls expected. With ADPCM, a single call consumes 52 Kbps, and if this call becomes a conference
call, another 52 Kbps is needed, yielding a total of 104 Kbps. From a broadband perspective, the first
available technology is 128 Kbps (ISDN), which leaves only 24 Kbps for other IP traffic. For
teleworking applications, where only a single call is needed, 128 Kbps can be used. For other sites on
the voice network, the minimum bandwidth recommended is 384 Kbps.
Various technologies, as shown in Table 14, are available from different service providers to provide IP
connectivity between locations.
Leased T1
Leased T1 facilities are the most robust WAN technology available. Leased T1s are point-to-point links
that inherently meet the network requirements for toll-quality voice because no ISP is involved.
Dedicated T1s are priced on a per-unit distance basis, making this a very cost-effective option over
short distances.
Table 14: IP Connectivity Chart
Technology
Upstream Bandwidth
Kbps
Downstream Bandwidth
Kbps
Calls with
ADPCM
T1 1544 1544 26
Frame Relay Varies Varies Varies
SDSL 1544 1544 26
SDSL 1024 1024 17
SDSL 768 768 13
SDSL 512 512 8
SDSL 384 384 6
IDSL 144 144 1 call only
ADSL 128 1,000 (varies) 1 call only
Cable 128 (varies) 1,000 (varies) 1 call only
ISDN BRI 128 128 Not supported
Dial-up
modem
28.8–56 28.8–56 Not supported
Note
Your bandwidth will vary, based on the WAN overhead for your particular system.