How to inform about disconnected Asterisk subscriber?

Question

Asterisk

Please tell me how to implement informing about a disconnected subscriber in Asteriske (13.14.0).
There is an internal subscriber (s) who, going on vacation or for some other reason, turned off the phone,
how to implement that the subscriber calling to this number would receive voice information, something like "the subscriber's device is turned off."

Answer 1

For example like this

exten => _XXXX,1,NoOp(-------INTERNAL-CALL----------)
  same => n,Set(DEVSTATE=${DEVICE_STATE(SIP/${EXTEN})})
  same => n,GotoIf($[ "${DEVSTATE}" = "UNAVAILABLE" ]?go-unvailable)
  same => n,Dial(${EXTEN},60,tT)
  same => n,HangUp
  same => n(go-unvailable),Noop(----unvailable----)
  same => n,PlayBack(silence/1&unvailable)
  same => n,HangUp