Hi All,
I have questions regarding signaling flow.
1.
UA1 <----------------------> B2BUA <-----------------------------> UA2
INVITE INVITE
------------------------------------>
--------------------------------------->
100 Trying 100 Trying
<---------------------------------
<-----------------------------------------
Let's say UA1 wants to cancel the call at this point.
Can B2BUA process two call legs separtely?
i.e Can B2BUA initiate 487 Request Terminated to UA1 after receiving 200 OK
response to CANCEL from UA1? If possible, canceling the call leg between
B2BUA and UA2 will be process as belows.
B2BUA sends CANCEL to UA2 and UA2 returns 487 Request Terminated to B2BUA.
B2BUA doesn't forward the 487 Request Terminated to UA1. B2BUA sends ACK
to 487 Request Terminated to UA2.
2.
UA1 B2BUA UA2
INVITE INVITE
------------------------------------>
--------------------------------------->
100 Trying 100 Trying
<---------------------------------
<-----------------------------------------
CANCEL
------------------------------------>
200 OK to CANCEL
<------------------------------------
200 OK to INVITE
<------------------
CANCEL
------------------>
2.1. Should B2BUA forward 200 OK response to INVITE to UA1 if B2BUA
receives the 200 OK after sending CANCEL to UA2?
2.2 Can B2BUA do the followings?
B2bUA sends 200 OK response to CANCEL to UA1 followed by 487 Request
Terminated. And B2bUA sends ACK to 200 OK to UA2 and then send BYE to UA2.
3. Can UA1 send BYE before sending final response to INVITE? if that is
possible, what is the expected behavior of B2BUA?
4. B2BUA had sent CANCEL to UA2. After that, It received BYE from UA1. But
it hasn't received a final response to INVITE yet. Can B2BUA forward BYE to
UA2? Is it necessary for B2BUA to wait for 200 OK response to CANCEL from
UA2 when it sends BYE to UA2?
5. If B2BUA receives BYE from UA1 shortly after B2BUA sent BYE to UA1,
which response should be sent by B2BUA? 200 OK or 491 Request Pending?
I would appreciate your support.
Regards,
Sumin
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