[SIPForum-discussion] Early Media Call flow

Joel Gerber Joel.Gerber at corp.eastlink.ca
Wed May 13 16:16:43 UTC 2015

The first 200 OK is in response to the PRACK and it completely legitimate and neither should be sent a BYE.

Joel Gerber
Network Operations Specialist - Telephone
Joel.Gerber at corp.eastlink.ca<mailto:%20Joel.Gerber at corp.eastlink.ca>    T: 519.786.1241

From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Stephen James
Sent: May-11-15 11:33 AM
To: Kamal Kandpal; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] Early Media Call flow

Looks like forking.

Check your Via header - if there are separate branch values then these are separate dialogs.
The UAC should cancel (BYE) the original dialog that sent PCMU / port 2000 and honor the port 5000 200 OK.

Stephen James
sjames_1958 at yahoo.com<mailto:sjames_1958 at yahoo.com>

We are not princes of the earth, we are the descendants of worms, and any nobility must be earned.

From: Kamal Kandpal <kamal.kandpal88 at gmail.com<mailto:kamal.kandpal88 at gmail.com>>
To: discussion at sipforum.org<mailto:discussion at sipforum.org>
Sent: Thursday, May 7, 2015 5:04 AM
Subject: [SIPForum-discussion] Early Media Call flow

Hi All ,

I have come across one sceanrio :

Invite sdp(O1)---------------------->

183 sdp V1(A1) <---------------------- PCMU codec , Audio port 2000

Prack --------------------- >

200 <----------------------

200 sdp V2 <---------------------------PCMA codec , Audio port 5000

ACK ------------------------------------->

Here Sdp coming in 183 and 200 is completely different and coming from different user Agent over same Call-id.

As offer answer is complete after 183 sdp ,how should we handle 200 coming with different sdp ?

1. Assuming 200 sdp as new offer and send answer in ACK ?

2. Ignore 200 sdp as offer answer already completed ?

As per RFC 6337 SDP should not be included in subsequent response once offer answer has been completed.



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