Specifications

Session Initiated Protocol
F – 2 ShoreTel, Inc.
SIP is supported for SIP trunks. SIP trunks will be assigned to a particular switch, like
any other trunk, so that SIP calls into and out of the ShoreTel system will be routed
through these trunks. However, up to five SIP trunks can be associated with one analog
switch port, meaning that there will be no physical channel/port associated with each
SIP trunk. The SIP trunk is a logical trunk end point which only handles call control
responsibilities. The media flows directly between the end-point SIP devices (i.e. call
initiator and the call terminator), freeing the switch from the burden of controlling
media flow.
WARNING We do not recommend placing Emergency 911 calls from SIP device.
ShoreTel supports SIP trunks, but does not support SIP extensions with this
release, thus users should not place 911 calls from any device that they
believe is a SIP extension.
NOTE SIP is not compatible with the conference bridge feature. If you have a
conference bridge installed, then you cannot turn on SIP. Similarly, if you install
ShoreTel 6 and use the SIP functionality, then you cannot use your conference
bridge. This incompatibility will be resolved with the upcoming Conference
Bridge version 5.6.
Supported RFCs
Support the following RFCs:
• 3261 - SIP
• 2976 - SIP Info
• 3891 - SIP Replaces
• 3515 - SIP Refer
• 3892 - SIP Referred-by
• 3361 - DHCP (for IPv4)
• 2396 - URI
• 2833 - DTMF
General SIP Comments
Conferencing
• Ports for MakeMe conferences must be available on the initiating side of a
conference call.
• MakeMe conference ports are needed even for 3-way conference. Note that
configuration of any MakeMe conferencing support in Director requires a
minimum of 4 available conference ports.
• 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. Similarly, dynamic SIP trunks also require that additional individual
dynamic SIP trunks are provisioned to handle calls that are placed on hold or for
conference-in calls.
DTMF
• With G.729, ShoreTel both sends and receives DTMF out of band per RFC 2833.
• With G.711, ShoreTel will only receive DTMF per RFC 2833. Not all ShoreTel
endpoints will send DTMF with G.711. For example, switches may not but
ShoreTel IP phones will.