Simple IVR with Timeout and Invalid Handling

A multi-attempt auto-attendant that replays the menu on bad input and hangs up gracefully after three failed attempts.

Dialplan

[ivr-main]
exten => s,1,Answer()
 same => n,Set(ATTEMPTS=0)
 same => n(menu),Set(ATTEMPTS=$[${ATTEMPTS} + 1])
 same => n,GotoIf($[${ATTEMPTS} > 3]?maxretry,1)
 same => n,Background(custom/welcome)
 same => n,WaitExten(5)

; Option routing
exten => 1,1,Goto(sales,s,1)
exten => 2,1,Goto(support,s,1)
exten => 0,1,Goto(operator,s,1)

; Invalid keypress -- replay menu, up to 3 times
exten => i,1,Playback(pbx-invalid)
 same => n,Goto(s,menu)

; Timeout waiting for input -- replay menu up to 3 times total, then give up
exten => t,1,GotoIf($[${ATTEMPTS} < 3]?s,menu)
 same => n,Goto(maxretry,1)

; Max retries reached
exten => maxretry,1,Playback(vm-goodbye)
 same => n,Hangup()

How it works

1. Attempt counter: ATTEMPTS increments on every pass through menu. After 3 tries (invalid or timeout), the call goes to maxretry and hangs up.
2. i (invalid): Fires when the caller presses a digit that matches no extension in the current context. Playback(pbx-invalid) tells them the input was not recognized, then the call loops back to the menu label.
3. t (timeout): Fires when WaitExten() expires with no input. On the first two timeouts it replays the menu; on the third it hangs up.
4. Background() vs Playback(): Background() listens for DTMF while the audio plays. A keypress interrupts the prompt immediately. Playback() ignores keypresses entirely; use it for error messages and farewells.

Tips

• Replace custom/welcome with a real recorded prompt. Record it at 8kHz mono and save as .gsm or .ulaw in /var/lib/asterisk/sounds/custom/.
• Keep WaitExten() to 5 seconds or less. Longer timeouts frustrate callers who are already listening to dead air.
• For multi-level IVRs, each menu level gets its own context. Use Goto() to move between them and reset ATTEMPTS when entering a new level.
• Add exten => #,1,Goto(s,menu) if you want callers to be able to replay the menu by pressing #.