Now that we've shown the basic syntax of include statements, let's put some include statements to good use. Include statements are often used to build chains of functionality or classes of service. In this example, we're going to build several different contexts, each with its own type of outbound calling. We'll then use include statements to chain these contexts together.
First, let's create a new context for local calls.
Remember that the variable ${EXTEN} will get replaced with the dialed extension. For example, if Bob dials 5551212 in the local context, Asterisk will execute the Dial application with SIP/provider/5551212 as the first parameter. (This syntax means "Dial out to the account named provider using the SIP channel driver, and dial the number 5551212.)
Next, we'll build a long-distance context, and link it back to the local context with an include statement. This way, if you dial a local number and your phone's channel driver sends the call to the longdistance context, Asterisk will search the local context if it doesn't find a matching pattern in the longdistance context.