Could I prevent a phone from making external calls?

This is possible for Room Phones, but not for User Phones. It might be useful for phones in a classroom where you want to be able to dial other internal extensions, but not make outside calls. Even if you block external calls, you will still be able to dial 911. This configuration change can be done by anyone with Offie Admin privileges on their Dialpad account (typically a principal, office manager, or receptionist). From the Admin Settings, click Desk Phones, Room Phones, click Options next to the phone and choose Edit and scroll down to the Outbound Calling section.