Installation guide

172 Planning and Installation Guide ShoreTel 14.2
Telephone Planning and Ordering Modems
9
The ShoreTel system supports distinctive ringing for inbound calls: calls from external parties have the
classic single ring, whereas calls from internal parties have a distinctive double ring. Some fax
machines detect the ringing pattern before answering and might not answer internal calls because of
the distinctive ring pattern. In particular, you must turn off the “Intelligent Ring Mode” on some Hewlett-
Packard fax machines to receive calls from internal parties.
Modems
The ShoreTel system supports “moderate-use” modem applications on the system. This is generally
considered to be modem calls up to 28.8 Kbps that do not last longer than 15 minutes. If your
application demands greater performance, you should bypass the ShoreTel system or move your
modem application to a pure IP-based solution.
The expected modem performance in different configurations is as follows:
 Analog connection speeds will not exceed 33.6 Kbps and could be lower. External factors,
including poor-quality trunk lines, ISP limitations, and multiple analog-to-digital conversions in the
network, can have a significant impact on connection speeds.
 Modem calls demand a high-quality network with virtually no packet loss. Packet loss should not
exceed 0.1%, which can be achieved on a local area network or in a wide area network using
leased T1 facilities.
 Analog trunk ports should not be used if a digital trunk (T1) is available, since performance will be
limited to 28.8 Kbps maximum. Digital trunks should be used instead.
 Connection speeds are significantly affected by multiple packet-to-circuit conversions (including
modem calls from one ShoreTel system to another). If a T1 line is used, modems should be able to
connect at K56Flex/V.90 or approximately 48 Kbps.