Classes of service allow you to control which numbers telephones may call. The called number is matched against the prefixes in the class of service, and the longest matching prefix is used. For example, calls to international numbers can be barred except for a single number which is specifically permitted. Alternatively, a single number can be barred if an employee is making unauthorised calls to it.

To create a class of service

1. Log in to the Enswitch web interface.
2. Go to Features » Classes of service.
3. Click the "New" button.
4. Enter the following:
   • A name for the group.
   • Optionally a description.
   • Whether internal and external calls are allowed by default. At this point you cannot enter specific destinations; see below.
5. Click the "Save" button.
6. On the list classes of service page, click the class you have made.
7. Click the "New" button.
8. Enter the full number or prefix, and whether to allow calls to it or not.
9. Click the "Save" button.
10. Add any other exceptions as desired.
11. In the settings pages for your telephone lines, there is a new option for the class of service. Set any telephone lines you wish to use this class of service. Any telephone line not in a class of service may call any number the system is configured for.