[asterisk-users] Dial command and its g option

[voip crazy]

I need to execute an action after a call is hangup. I just see the
command Dial has an option for that, the "g" option.
I configure the dial command as

exten => s,n,Dial(SIP/100,100,Ttg)

How should I add the line which the command will be executed after the
dial command in this example?

I don`t how its works, someone could put a example about the way to use it.

Thanks you in advance.

VoipCrazy