A method and apparatus are provided for transmitting a Session Initiation Protocol message by {HEAD ~ a User Equipment} in {TAIL ~ an idle mode} in an Internet Protocol Multimedia Subsystem system 
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A method and apparatus are provided for transmitting a Session Initiation Protocol message by { HEAD ~ a User Equipment } in { TAIL ~ an idle mode } in an Internet Protocol Multimedia Subsystem system
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH