ShoreTel IP8000 Application Note page 7

The next item to change for the SIP trunk groups is the outbound trunk configuration (Figure 11).
For the Outbound Trunk Configuration set the "Access
Code" and "Local Area Code" fields for the system. For the
"Trunk Services" boxes, typically none of these will be
selected, except for "Caller ID not blocked by default", if
not enabled the IP8000 will not receive Caller ID information
when calls are sent via this trunk group.
Figure 11 – Outbound Trunk Configuration
Note:
ShoreTel system to the conference phone.
After these settings are made press the "Save" button to
input the changes.
Remember, these are calls being sent from the
IP8000 Conference Phone Application Note—Page 7