According to RFC 3515, Contact is mandatory for a REFER request and its 2xx response (see table 1 on page 3 & 4). Section 2 also clearly states that the REFER MUST have a Contact.
A REFER request implicitly establishes a subscription to the refer event. Event subscriptions are defined in [2]. A REFER request MAY be placed outside the scope of a dialog created with an INVITE. REFER creates a dialog, and MAY be Record-Routed, hence MUST contain a single Contact header field value. REFERs occurring inside an existing dialog MUST follow the Route/Record- Route logic of that dialog. Any request that can create a dialog (e.g INVITE, SUBSCRIBE, REFER) must have a Contact, even when it is sent within an existing dialog. cheers, (-:bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Iñaki Baz Castillo Sent: Wednesday, February 04, 2009 9:38 AM Cc: [email protected] Subject: Re: [Sip-implementors] [Sip] Is Contact Header mandatory in REFER message? 2009/2/4 Bob Penfield <[email protected]>: > No, a request that is creating a dialog does not have a to-tag. If it has a > to-tag, its an in-dialog request. In that case, the REFER would be a target > refresh request. Sorry, my fault. What I wanted to say is that a initial-request REFER doesn't require "Contact" since initial-request REFER doesn't create a dialog, does it? Since the usage of REFER as initial-request is not very documented perhaps I'm wrong (does the implicit subscription also exist for initial REFER?). Thanks. -- Iñaki Baz Castillo <[email protected]> _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
