Hi all!
I have a question regarding how a B2BUA should handle session timer. The
current case is that a call between A and B goes via a B2BUA, the B2BUA uses
session timers to be able to have somewhat secure billing, but A and B does
not support Session Timer. So what will happen is that after time x is that
B2BUA must refresh the session timer towards B (I consider it enough to have
session timer on one call leg). The problem is how to handle SDP data.
1) Only reInvite and Update is allowed to be used to refresh session timers
(as according to RFC4028), right?
If B2BUA would use reInvite, if it send a reInvite to B without any SDP
data, B migth add a SDP offer in the 200 OK response which means I have to
have a SDP response in the ACK... and I cant really do this without
including A... which I dont want to do (cant send the 200 OK to A to get SDP
response since A did not trigger reInvite)
2) Is there some way to send an reInvite, and indicate to the recipent (in
this case B), that B should not insert a SDP offer in the 200 OK?
The other option would be for B2BUA to refreash the session by generating an
Update to B when timer x triggers.
3) Is it allowed to send an UPDATE request without a SDP body? Since there
is no ACK to 200 OK of a Update I guess it is not valid for B to add a SDP
offer in 200 OK, which will prevent me from having the same problems as in
2)...
4) What would be the expected behavior of a UA that receives an update
without a SDP body? Just to keep the current voice/video session as usuall?
Thanks in advance!
// Andreas
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