Tandem Trunking Trunk Planning and Ordering 5
ShoreTel 14 Planning and Installation Guide 97
To block all outbound caller ID numbers from being sent, you can configure the PRI trunk group to
always block the caller ID number.
On wink-start and loop-start trunks, the outbound caller ID is defined by the service provider.
On T1 PRI and loop-start trunks, users can override the Caller ID Blocking configuration on a call-
by-call basis by using commands at the telephone, such as *67, *82. Users cannot override the
Caller ID Blocking configuration of wink-start and E1 PRI trunks.
For more information on configuring outbound caller ID, please refer to the ShoreTel System
Tandem trunking allows legacy voice systems to utilize a ShoreTel system for outbound dialing. The
ShoreTel system supports both user-side and network-side PRI, allowing ShoreTel systems to flexibly
support digital tie trunks to other systems.
You can enable tandem trunking support for any PRI trunk group with a check box in ShoreTel Director.
Tandem calls are associated with a user group for outbound trunk selection. Inbound calls recognized
as tandem calls are redirected to an outbound trunk based on user group call permissions and trunk
group access. When needed, a “dial-in prefix” can be specified that is prepended to digits collected on
tandem calls. The concatenated set of digits is then used in outbound trunk selection for the tandem
The addition of network-side PRI support makes PRI tie trunks easier and more compelling to deploy.
ShoreTel Voice Switches that support T1 PRI can act as either the user-side or network-side of a PRI
tie trunk. The tie trunk may be used to tie a ShoreTel system to a legacy voice system, or potentially to
another independent ShoreTel system.
Performing Traffic Calculations
The number of trunks required on your system will vary depending on the number of users and your
specific application needs. It is important to order your trunking correctly; too few can lead to blocked
calls when all trunks are busy, and too many trunks can lead to wasted money on monthly access
For information about calculating the trunk requirements, refer to Planning and System Design on