The VMS will be responsible for {HEAD ~ its normal function} of telling {TAIL ~ the caller} that the called extension was not available and recording a message for the extension called 
of telling
The VMS will be responsible for { HEAD ~ its normal function } of telling { TAIL ~ the caller } that the called extension was not available and recording a message for the extension called
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH