[Freeswitch-dev] Handling of multiple 183 responses with different SDP

[Michael Jerris]

http://www.ietf.org/rfc/rfc3264.txt


On Oct 27, 2010, at 7:15 AM, Irina Ivanova wrote:

> Hi! We are getting the same problem as described in the jira ticket with 
> key FS-715:
> http://jira.freeswitch.org/browse/FS-715?page=com.atlassian.jira.plugin.system.issuetabpanels%3Aall-tabpanel
> 
> Our provider is also sending us more than one 183 Session progress 
> response, each of them with SDP where destination IP address is the same 
> but the UDP ports are different.
> 
> If is needed I can provide the pcap file where you can see that after 
> receiving of second 183 Session progress response (with updated SDP) 
> Freeswitch continues to listen on an old port. As a consequence, no 
> audio can be heard.
> 
> Our provider assures us that sending of more than one 183 Session 
> progress responses is completely standard behavior that does not violate 
> SIP RFC 3261 and is handled correctly by any ATA VoIP.
> We verified the Asterisk behavior in this case, and can say that it 
> handles receiving of multiple 183 Session progress responses without any 
> problems and changes the UDP port each time it gets changed in session 
> description inside of 183 response.
> 
> Our provider gave us a reference to SIP RFC 3261:
> 
> 13 Initiating a Session
> 13.1 Overview
> "Before sending a final response, the UAS can also send provisional 
> responses (1xx) to advise the UAC of progress in contacting the called user.
> After possibly receiving one or more provisional responses, the UAC will 
> get one or more 2xx responses or one non-2xx final response."
> 
> "one or more provisional responses" was underlined by our provider and 
> in addition to this was said that there is no any place in RFC from 
> which you can conclude that you can not send more than one SIP 183 
> Session Progress response.
> 
> We also found a document regarding 183 response:
> http://tools.ietf.org/html/draft-ietf-sip-183-00
> 
> Here are some references to the parts talking about temporary media and 
> session description change:
> 
> 4.2. Change of Temporary Media
> 
>   After a temporary media stream has been established, its parameters
>   can be changed by sending further provisional responses that also
>   contain session descriptions. Upon receipt of such a response, the
>   client MUST immediately cease transmission of media relating to the
>   old temporary stream. As before, the new temporary media stream is
>   established after acknowledgement of the provisional response.
> 
>   Provisional responses which contain no session description SHOULD NOT
>   have an effect on any currently established temporary media stream.
> 
> 
> 5.11.7 Caller Receives 183 Response
> 
>   When the calling UA receives a 183 response that contains a session
>   description and an indication that the session description is for
>   early media, it SHALL setup the associated media session and present
>   any media received from the called UA to the user.
> 
> 
> Again nothing is said about multiple 183 responses specifically, only 
> about multiple provisional responses in general.
> So, is there anything that can be done to resolve this issue?
> Thanx,
> Irina
> 
> -- 
> ================================================================
> 
> Distinti saluti
> --
> 
> Irina Ivanova
> Settore Sviluppo MasterVoice
> 
> tel: +39 0522 1846007
> fax: +39 0522 331673
> mob: +39 334 6449290
> e-mail: i.ivanova at mastervoice.it
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> 
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