Installation guide

Fax Machines and Modems Telephone Planning and Ordering
9
ShoreTel 14.2 Planning and Installation Guide 171
**Indicates uncertainty as to whether country supports configured standard.
Fax Machines and Modems
The ShoreTel system supports fax machines and modems in the United States and Canada (and not
elsewhere).
Fax and modem calls are more sensitive to network problems than voice conversations. The human
ear does not notice a lost packet during a voice conversation, but when a packet is lost during a fax
transmission the line may be dropped. During a modem call, a lost packet can cause a retransmission.
In the worst case, fax machines and modems will not establish a connection or may drop the call
altogether. In general, fax and modem calls work across a local area network, but work on wide area
networks only when there is virtually no packet loss and little jitter.
The ShoreTel system automatically detects both fax and modem tones, and boosts the voice encoding
to a higher value to increase throughput. (G.711 at 64 Kbps is recommended.) It also stops the
nonlinear processing of the echo canceller and fixes the size of the jitter buffer to a preset level. In
addition, for modems, the echo canceller is frozen or stopped, since the modems use their own
network echo cancellers.
Fax Machines
Fax machines require a high-quality IP network for proper operation.
None Malaysia
None Brazil
None Netherlands
None New Zealand
None Portugal
None Belgium
None Denmark
None Sweden
None India
None Japan
None Finland (unsupported DTMF variation)
None Greece
None Bulgaria
Table 30: Caller ID Standard Support for Analog Phones by Country (Continued)
Caller ID Standard Country