System information

exten => i,1,Playback(pbx-invalid)

same => n,Goto(incoming,123,1)

exten => t,1,Playback(vm-goodbye)

same => n,Hangup()

You’ll notice we’ve added pseudonym extension names for our extension numbers. In

“Extensions” on page 110, we explained that Asterisk does not care which naming

scheme you use to identify an extension. We’ve simply added both numeric and named

extension identifiers for reaching the same endpoint; extensions 100 and leif both

reach the device located at SIP/0000FFFF0001, extensions 101 and jim both reach the

device located at SIP/0000FFFF0002, and both 102 and russell reach the device located

at SIP/0000FFFF0003. The devices are identified with the global variables ${LEIF}, $

{JIM}, and ${RUSSELL}, respectively, and we’re dialing those locations using the

Dial() application.

In our test menu we’ve simply picked a couple of random endpoints to dial, such as

DAHDI/1 and SIP/Jane. These could be replaced with any available endpoints that you

wish. Our TestMenu context has been built to start giving you an idea as to what an

Asterisk dialplan looks like.

Pattern Matching

If we want to be able to allow people to dial through Asterisk and have Asterisk connect

them to outside resources, we need a way to match on any possible phone number that

the caller might dial. For situations like this, Asterisk offers pattern matching. Pattern

matching allows you to create one extension in your dialplan that matches many dif-

ferent numbers. This is enormously useful.

Pattern-matching syntax

When using pattern matching, certain letters and symbols represent what we are trying

to match. Patterns always start with an underscore (_). This tells Asterisk that we’re

matching on a pattern, and not on an explicit extension name.

If you forget the underscore at the beginning of your pattern, Asterisk

will think it’s just a named extension and won’t do any pattern match-

ing. This is one of the most common mistakes people make when start-

ing to learn Asterisk.

After the underscore, you can use one or more of the following characters:

Matches any single digit from 0 to 9.

Matches any single digit from 1 to 9.

Building an Interactive Dialplan | 125