You can do it using WaitExten [1]:
[callme]
exten => s,1,Answer
exten => s,n,Playback(demo/${FILENAME1})
exten => s,n,WaitExten(3)
exten => s,n,Goto(s,1)
exten => 1,1,Noop(user pressed 1)
exten => 1,n,Goto(however-shall-go-to-when-pressed-1)
exten => 2,1,Noop(user pressed 2)
exten => 2,n,Goto(however-shall-go-to-when-pressed-2)
Using extensions patterns [2]:
[callme]
exten => s,1,Answer
exten => s,n,Playback(demo/${FILENAME1})
exten => s,n,WaitExten(3)
exten => s,n,Goto(s,1)
exten => X,1,Noop(user pressed ${EXTEN})
exten => X,n,Goto(however-shall-go-to-when-pressed-${EXTEN})
here is exactly what you requested:
[callme]
exten => s,1,Answer
exten => s,n,Playback(demo/${FILENAME1})
exten => s,n,WaitExten(3)
exten => s,n,NoOp(going on - no dtmf detectd)
exten => X,1,Noop(user pressed ${EXTEN})
exten => X,n,Goto(s,1)
also take a look at background asterisk application [3].
REFERENCES:
[1] http://www.voip-info.org/wiki/view/Asterisk+cmd+WaitExten
[2] http://www.voip-info.org/wiki/view/Asterisk+Dialplan+Patterns
[3] http://www.voip-info.org/wiki/view/Asterisk+cmd+BackGround