For your SIP trunk numbers, you can customize the allowed calling area by phone number in Control Center. For example, you can block all outbound calls for a number except to local numbers or you can allow long-distance calls, but not international calls.
To customize the calling area for a phone number:
Control Center displays the phone numbers on that SIP service ID. You can view what types of calls are blocked for each number (if any) and edit the calling areas for the numbers to either block or unblock calling areas.