exten => 5555,1,ChanIsAvail(SIP/1188)
exten => 5555,2,Noop("002 " ${AVAILCHAN})
exten => 5555,3,Noop("003 " ${AVAILSTATUS} )
exten => 5555,4,Noop("004 --------")
exten => 5555,5,Noop("005 " ${AST_DEVICE IN USE}) 
exten => 5555,6,Noop("006 " ${AST_DEVICE_UNAVAILABLE})
exten => 5555,3,Noop("007 " ${AVAILSTATUS}

exten => 5555,102,Noop("102 " ${AVAILCHAN})
exten => 5555,103,Noop("103 " ${AVAILSTATUS}
exten => 5555,104,Hangup