\section{{\BYE}}
\label{sec:BYE}

The user agent client uses {\BYE} to indicate to the server that it
wishes to release the call leg.  A {\BYE} request is forwarded like an
{\INVITE} request and {\MAY} be issued by either caller or callee.  A
{\BYE} request {\SHOULDNOT} be sent to terminate a pending call request
which has not generated either a final response or a provisional
response containing a \header{To} tag.  A party to a call {\SHOULD}
issue a {\BYE} request before releasing a call (``hanging up'').  A
party receiving a {\BYE} request {\MUST} cease transmitting media
streams specifically directed at the party issuing the {\BYE} request.

A UAS receiving a {\BYE} request {\MUST} respond to any pending
requests received for that call, including {\INVITE}. It is {\RECOMMENDED}
that a 487 response is generated. 

This method {\SHOULD} be supported by user agent servers.
