Pre-dial handlers allow you to execute a dialplan subroutine on a channel before a call is placed but after the application performing a dial action is invoked. This means that the handlers are executed after the creation of the caller/callee channels, but before any actions have been taken to actually dial the callee channels. You can execute a dialplan subroutine on the caller channel and on each callee channel dialleddialed.
There are two ways in which a pre-dial handler can be invoked:
Handlers For Dial or FollowMe, handlers are invoked using similar nomenclature as other options (such as M or U) in Dial or FollowMe ) that cause some portion of the dialplan to execute.
The examples illustrated below use the following channels:
- SIP/foo is calls calling either SIP/bar, SIP/baz, or both
- SIP/foo is the caller
- SIP/bar is a callee
- SIP/baz is another callee