UA-B can not recognize that a glare situation is occurring in the following two sequences.
And only UA-A can recognize that there is a possibility that the glare situation may have occurred.
SUGGESTION:
If the S-E header of the two responses are different, UA-A SHOULD generate a new UPDATE request in order to make sure that both UAs have a common view of the state of the session-timer.
BACKGROUND:
E-mail: http://www.ietf.org/mail-archive/web/sipcore/current/msg09272.html
UA-B can not recognize that a glare situation is occurring in the following two sequences. And only UA-A can recognize that there is a possibility that the glare situation may have occurred.
SUGGESTION: If the S-E header of the two responses are different, UA-A SHOULD generate a new UPDATE request in order to make sure that both UAs have a common view of the state of the session-timer.