Hi, Contact header SHOULD be present in target-refresh requests ( changes the Remote Target of the dialog) within a dialog and the corresponding 2xx response. Its not mandatory for rest of the requests and responses. Re-INVITE and UPDATE are target refresh requests.
Section 12.2.1 in rfc 3261 says - A UAC SHOULD include a Contact header field in any target refresh requests within a dialog, and unless there is a need to change it, the URI SHOULD be the same as used in previous requests within the dialog However, Table 1 in rfc 3311 shows that Contact is mandatory in UPDATE as well as the 2xx response for it, I wonder it is so. Thanks, Pranab ________________________________________ From: [email protected] [[email protected]] On Behalf Of Alok 2 Tiwari [[email protected]] Sent: Tuesday, November 06, 2012 4:05 PM To: 'Tamjid Ali'; [email protected] Subject: Re: [Sip-implementors] Is contact header mandatory for each sip messages? Hi Tamjid, As per RFC-3261, Contact is optional in 1xx but it is mandatory in 2xx. Refer table in section 20.1. Header field where proxy ACK BYE CAN INV OPT REG ___________________________________________________________ Contact R o - - m o o Contact 1xx - - - o - - Contact 2xx - - - m o o Contact 3xx d - o - o o o Contact 485 - o - o o o Contact is mandatory in INVITE request and 2xx response of INVITE. 1xx is also used for making early dialog however 2xx response only comes from the final destination. Regards, Alok Tiwari Aricent -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tamjid Ali Sent: Saturday, November 03, 2012 10:09 AM To: [email protected] Subject: [Sip-implementors] Is contact header mandatory for each sip messages? Hi,Can anyone clear me why contact header present in each sip message even after knowing each other after 1xx response? If contact header is not present in subsequent sip messages then what will happen?? Thanks®ards,Ali _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors =============================================================================== Please refer to http://www.aricent.com/legal/email_disclaimer.html for important disclosures regarding this electronic communication. =============================================================================== _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors SASKEN BUSINESS DISCLAIMER: This message may contain confidential, proprietary or legally privileged information. In case you are not the original intended Recipient of the message, you must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message and you are requested to delete it and inform the sender. Any views expressed in this message are those of the individual sender unless otherwise stated. Nothing contained in this message shall be construed as an offer or acceptance of any offer by Sasken Communication Technologies Limited ("Sasken") unless sent with that express intent and with due authority of Sasken. Sasken has taken enough precautions to prevent the spread of viruses. However the company accepts no liability for any damage caused by any virus transmitted by this email. Read Disclaimer at http://www.sasken.com/extras/mail_disclaimer.html _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
