Hi All,
Let's assume a scenario where B2BUA forks the incoming call for a user
to two UA's, UA2 & UA3.
SIP message flow for this is:
UA1 B2BUA UA2
UA3
---------INVITE---------->
(Call-ID=c1)
(From tag=f1)
----------INVITE-------->
(Call-ID=c2)
(From tag=f2)
------------------INVITE------------------>
(Call-ID=c3)
(From tag=f3)
<-----------------180----------------------
(Call-ID=c3)
(From tag=f3)
(To tag=t3)
<----------180------------
(Call-ID=c1)
(From tag=f1)
(To tag=t1)
<---------180------------
(Call-ID=c2)
(From tag=f2)
(To tag=t2)
(Require=100rel)
<----------180------------
(Call-ID=c1)
(From tag=f1)
(To tag=t11)
(Require=100rel)
<-----------------200----------------------
--------CANCEL--------->
<--------200------------
As per our internal design after receiving final response from UA3,
B2BUA will CANCEL the call towards UA2.
But we can't send 200OK to UA1 as a PRACK is pending on
dialog(c1+f1+t11).
Thus I have few queries on it:
1) Can B2BUA send a CANCEL to UA2 before PRACK transaction is over?
2) If answer to above question is "yes" then how can B2BUA send
200OK for dialog(c1+f1+t1) to UA1?
Are there any alternate & better way to handle this call flow?
Thanks,
Puneet
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