Hi You are right there is no quote in RFC that restricts such a behavior. Looks like the peer with which you are testing is not sending SDP in 180 response, and hence does not need it's acknowledgement (PRACK) back from the UAC.
However, there is one condition for sure when is not permitted. If the initial INVITE contained 100rel option tag in Require header, then the UAS must send all provisional responses (except 100 Trying) reliably. Refer to the following quote from RFC 3262 :: Sec 3 UAS Behavior The UAS MUST send any non-100 provisional response reliably if the initial request contained a Require header field with the option tag 100rel. If the UAS is unwilling to do so, it MUST reject the initial request with a 420 (Bad Extension) and include an Unsupported header field containing the option tag 100rel. Regards Rohit Aggarwal Aricent -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Rockson Li (zhengyli) Sent: Thursday, November 20, 2008 9:02 AM To: [email protected] Subject: [Sip-implementors] Can UAS send interleaving reliable/unreliableresponse Hi folks, Can UAS send interleaving reliable/unreliable response, like first a reliable 183, then a unreliable 180? A B |-----------------------------| |INVITE---------------------->| |<-------------------100Trying| |<---------------183(reliable)| |PRACK----------------------->| |<-------------180(unreliable)| | | Looking through RFC3262, I don't find any text against this behavior, though it's very unusual. This is a real life case during interop test. So I would like to hear your comments on B's operation. many thanks Regards, -Rockson _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors "DISCLAIMER: This message is proprietary to Aricent and is intended solely for the use of the individual to whom it is addressed. It may contain privileged or confidential information and should not be circulated or used for any purpose other than for what it is intended. If you have received this message in error,please notify the originator immediately. If you are not the intended recipient, you are notified that you are strictly prohibited from using, copying, altering, or disclosing the contents of this message. Aricent accepts no responsibility for loss or damage arising from the use of the information transmitted by this email including damage from virus." _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
