Domains with Non-Overlapping Extensions
If you have domains with non-overlapping extensions, use the following instructions to configure your interdomain dialing. (DIDs, by nature, are non-overlapping.)
- For each domain, create a dial plan entry with Try Loopback in the Trunk field.
- Enter * for both pattern and replacement.
Note: Be sure to place the loopback dial plan entry at the top of the dial plan; however, 911, 411, 611, etc., can be the topmost entries.
Domains with Overlapping Extensions
If the extensions between the different domains are overlapping, users will need to dial a prefix before the actual extension number is dialed. For this configuration, you will need to designate a prefix and provide proper pattern and replacement strings. Note: Prefixing simply makes extension numbers non-overlapping; however, prefix-based dialing can be used for both overlapping and non-overlapping extensions.
- From the first domain, create a gateway trunk that will be used to dial to the other domain(s).
- Create a dial plan entry that uses the gateway trunk just created.
- Choose a prefix. Be sure to choose a prefix that doesn’t conflict with your other extensions (i.e., if the domain has extensions beginning with 5, you must use a number other than 5).
For the Pattern field, enter the prefix you’ve chosen followed by a string that corresponds with the number of digits your extensions have. The example shown below is useful for three-digit extensions and will require users to dial a 6 before dialing the extension number (e.g., if the user dials 6400, extension 400 will be called).
- For the Replacement field, enter sip:\1@\r;user=phone. (It is not necessary to specify the domain name here. The PBX will use whatever is configured on the trunk.)
- Repeat these steps from the other domain(s).