A closer look at RFC 3261 will explain that the methods listed in Allow header are to be invoked from within a dialog:
Sec 13.2.1 -> An Allow header field (Section 20.5) SHOULD be present in the INVITE. It indicates what methods can be invoked within a dialog, on the UA sending the INVITE, for the duration of the dialog. For example, a UA capable of receiving INFO requests within a dialog [34] SHOULD include an Allow header field listing the INFO method. Section 13.2.2.1 -> Header fields present in a provisional response are applicable as long as the dialog is in the early state (for example, an Allow header field in a provisional response contains the methods that can be used in the dialog while this is in the early state). Section 10.2 -> A REGISTER request does not establish a dialog. And the assumption that ' Since REGISTER is one of the necessary operations' is completely absurd. Section 10.2.1 indicates that a "A SIP UA can choose to register...". This notion is especially true for B2BUAs and peer to peer calling. A UA may or may not choose to register. I hope this helps. Regards, Gaurav -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Wednesday, November 01, 2006 12:59 PM To: sip-implementors@cs.columbia.edu Subject: [Sip-implementors] Allow header field Rfc 3261 section 20.5 says :- "All methods, including ACK and CANCEL, understood by the UA MUST be included in the list of methods in the Allow header field, when present." My question whether REGISTER Method is to be added in Allow header field or not? Because REGISTER is also one of the sip methods. Since REGISTER is one of the necessary operations we don't add it? Thanking you, Waiting for your reply, ---Sumit _______________________________________________ Sip-implementors mailing list Sip-implementors@cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
