Installation guide

DTMF Session Initiation Protocol
D
ShoreTel 14.2 Planning and Installation Guide 393
 An individual SIP trunk must be provisioned for each call to the SIP device (including conference-
in or transferred calls). Thus, static SIP trunks must be provisioned with additional trunks in line
with the highest anticipated number of such calls.
DTMF
ShoreTel supports RFC2833 (DTMF) for users calling over SIP trunks regardless of the negotiated
voice codec.
ShoreTel can be configured to use SIP INFO for DTMF signaling in environments where out-of-band
DTMF is needed but RFC 2833 is not applicable. SIP INFO for DTMF signaling is available on only SIP
trunks.
Foreign Language Support
In addition to English, ShoreTel support other languages (for Caller Name, Called Name, User Name,
and so on) over SIP tie trunks and service provider trunks. Some third-party devices might not be able
to display all of a languages’ characters.
General Feature Limitations
 A music on hold (MOH) switch supports 15 streams of MOH, but some of these can be used to fan
out MOH to other trunk switches. If some MOH streams go to other switches, the actual number of
MOH streams on SIP trunks is less than 15.
 Three-way conference on a SIP trunk call uses Make Me conference ports. A minimum of 3 Make
Me ports must be configured to support 3-way conferencing.
 A SIP trunk can be a member of a 3-party conference but cannot initiate a 3-way conference
(unless the SIP device merges the media streams itself).
 ShoreTel SIP supports basic transfers (blind transfers) and attended transfers (consultative
transfers).
 In the current release, the following features are supported by SIP only if the trunk has a SIP trunk
profile with hairpinning and the trunk is on a half-width switch:
 Silent Coach
 Silent Monitor
 Barge-In
 Call recording
 Silence detection on trunk-to-trunk transfers is not supported because it requires a physical trunk.
 Extension Assignment is limited using SIP trunks. Either DTMF over INFO must be used, or in—
the absence of such support—the features that use DTMF are not supported (including “Accept
call by pressing 1.”)
 Fax (and modem) redirection on SIP trunks is supported if T.38 is used.