Specifications

Session Initiated Protocol
F – 4 ShoreTel, Inc.
• 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 (i.e. blind transfers) and attended transfers
(i.e. consultative transfers).
Note: ShoreTel has determined the Polycom SIP phone cannot transfer calls
although you can transfer call to the Polycom SIP phone.
• Silent Monitoring is not supported on a SIP trunk call.
• Barge-In is not supported on a SIP trunk call.
• Call recording is not supported on a SIP trunk call. Call recording requires
presence of a physical trunk in the call.
• Call redirection by SIP devices is not supported.
• Park/Unpark is not supported on a SIP trunk call. This is planned for a future
release.
• Office Anywhere is not supported on SIP trunks. Outbound trunk hunting will
automatically avoid SIP trunks when placing the call to the Office Anywhere user.
The call to the Office Anywhere user cannot be a SIP trunk; however, the call to
the external party can be a SIP trunk.
• Silence detection on trunk-to-trunk transfers is not supported since it requires a
physical trunk.
• Fax redirection is not supported with SIP trunks as only physical trunks can detect
fax tones.
• Incoming calls that come through a ShoreGear trunk to a fax machine that has
been hooked up to a SIP analog gateway may not work due to failure to detect the
fax tone on the trunk-side and hence, failure to switch to "fax mode"
• Simulated ringback is not provided when calling a Work Group or Hunt Group
from a SIP trunk. This is planned for a future release.
• ShoreTel SIP supports two codecs - G.711 and G.729.
• G.711 SIP devices which do not support RFC 2833 DTMF cannot talk to
Voicemail (VM) or Auto-Attendant (AA).
• G.729 only SIP devices cannot talk to VM/AA unless they are configured as
Teleworkers or configured in remote site.
• SIP devices cannot have a voicemail box, cannot use PCM, cannot be a member of
a hunt group, cannot be a member of a workgroup, and will not appear in the dial
by name directory of the AA because they are SIP trunks and not SIP extensions.
Additional Configuration Considerations
• SIP Info configuration in a Trunk Group should be enabled if ShoreTel SIP tie
trunks are used.
• Overlapping number plans are not allowed between two systems tied with SIP
trunks unless digit translation is used.
• When translating digits between two ShoreTel systems tied with SIP trunks, even
system extensions like VM, AA should be properly translated.
• SIP devices should either be physically present in the ShoreTel site where the
ShoreGear switch is hosting the SIP trunk or should be out of the ShoreTel
network.
• A SIP trunk group cannot host both dynamic and static SIP trunks simultaneously.
• SIP trunk group hosting dynamic SIP trunks cannot span ShoreGear switches.
• ShoreTel working with Dynamic Trunks: