Whenever we need to route outbound calls through different trunks, we can use different prefixes, or patterns, or use a set of passwords (PIN Sets), or even use a trunk sequence. When our PBX has more than one trunk or line and we want to route calls in a more intelligent way, we must take advantage of the features that we currently have in our system. In this section, we will show a set of recipes for controlling outbound calls.
The simplest way to differentiate routes is by creating outbound routes with different dialing prefixes. This is helpful if we'd like to route local calls through one specific trunk and long-distance calls through another.
Just create an outbound route with a different prefix. If we want to use the E1 trunks, we use prefix 9; if we'd like to call through the analog lines, we use prefix 8; and so on. The next picture shows the different routes associated to different trunks:
