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 a list of all services assigned to the accounts under your enterprise ID. If you have more than ten services, you can view the rest of your services by clicking one of the blue linked Show numbers at the top of the list or you can click the blue down arrow at the bottom of the list to add ten services at a time to the view.