The Hangup application
The last line of our simple dialplan executes the Hangup application (same => n,Hangup()):
exten => 999,1,Answer() same => n,Playback(this-call-may-be-monitored-or-recorded) same => n,Hangup()
This application is usually used at the end of a context to hang up the active call. This ensures that the line will be hung up after the end of the conversation and the call doesn’t continue on in the dialplan.