Chapter F: Session Initiation Protocol Overview
ShoreTel 8 Planning and Installation Guide 293
•ShoreTel 8 offers support for RFC2833 (DTMF), so if the voicemail server is down,
external callers can now enter an extension using DTMF to ring the extension of
the user they are trying to reach. This allows callers who are accessing the ShoreTel
system over a SIP trunk to have access to the Backup Auto-Attendant in the same
manner as users who are accessing the system via all other trunk types.
F.1.2.3 Foreign Language Support
•In addition to English, ShoreTel will support Spanish, French and German (Caller
Name, Called Name, User Name) over SIP tie trunks and service provider trunks,
although certain third-party devices may not be able to display the Spanish or
F.1.2.4 Routing with Static and Dynamic Trunks
•From the trunk group perspective, when static and dynamic trunks are used:
— only one trunk group with dynamic trunks is allowed per switch
❋outbound calls to this trunk group must be completed based in the
❋calls to the same IP address will not work
❋calls to different devices going to the PSTN will be selected randomly
— Trunk groups with static IP addresses will not route calls based on OSE ranges
due to the fact that static trunks do not need registration
❋the switch sends the call to the next available trunk instead of sending it to
the correct OSE within the range
❋this issue can be solved by creating a trunk group on a per-device basis
— OSE's routed over trunk groups in more than one switch (with dynamic
trunks) will fail
F.1.2.5 General Feature Limitations
•Incoming calls to an IP phone placed over a SIP tie trunk (via G729) require the IP
phone user to press the “To VM” soft key twice in order to successfully transfer the
caller to voice mail.
•ShoreTel 8 introduces support for Music On Hold (MOH) over SIP trunks. The
capacity limits of MOH switches will not change (i.e. a switch will still be capable
of providing up to 15 streams). However, these streams can be to other switches or
to SIP devices, so customers who were not at the switch capacity limit before may
now find themselves testing the limits of the switch capacity.
•If the ShoreTel server has a conference bridge 4.2 installed, you should not enable
SIP. The conference bridge is not compatible with a ShoreTel system that has SIP
enabled due to the dynamic RTP port required for SIP.
•3-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. Make Me
conferencing for 4 to 6 parties is not supported.
•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).