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PRACK with early media


Hi all,

I've run into some problem(?) with PRACK towards a SIP trunk which support early media.
The SIP trunk(UAS) responds to an INVITE with a 183 Session Progress to which the SIP trunk requires PRACK.
The DUM acknowledge this and sends a PRACK to which the SIP trunk responds with a 200 OK.

At this point the SIP trunk sends a new 183 Session Progress including the previous SDP as well as stepping up the RSeq.
This signal the DUM doesn't PRACK, and so the SIP trunk keeps re-transmitting the signal.


UAC                                           UAS(Sip trunk)
 |------------------INVITE(offer)-------------->|
 |<------------------100 Trying-----------------|
 |<----183 Session Progress(answer)---|
 |--------------------PRACK------------------->|
 |<------------------200 OK---------------------|
 |<----183 Session Progress(answer)---|
 |<----183 Session Progress(answer)---|
 |<-----------504 Server Time-out-----------|
 |-----------------------ACK-------------------->|

Now is this a valid case? What am I missing?

I'm using version 1.10.0.

BR
/Janne