Determining Support for UPDATEs Clause Samples

Determining Support for UPDATEs. When a UAS compliant to this specification receives an INVITE request for a new dialog, and generates a reliable provisional response containing SDP, that response SHOULD contain an Allow header field that lists the UPDATE method. This informs the caller that the callee is capable of receiving an UPDATE request at any time. An unreliable provisional response MAY contain an Allow header field listing the UPDATE method, and a 2xx response SHOULD contain an Allow header field listing the UPDATE method.