/mcpComments Supported in Unified Communications Manager SIP Headers — No Content Language — Yes Content-Length See 'Supported Content Types'. Yes Content-Type — Yes CSeq — Yes Date — No Error-Info — Yes Expires — Yes From — No In-Reply-To Unified CM sets to 70 for outgoing INVITE and does not increment/decrement it. Yes Max-Forwards This header gets used with REFER. Yes MIME-Version — Yes Min-Expires — No Organization — No Priority Unified CM SIP supports receiving this header in 407 responses. Yes Proxy-Authenticate Unified CM SIP supports sending a new request with this header after it receives 407 responses. Yes Proxy-Authorization — No Proxy-Require — Yes Record-Route — No Reply-To — Yes Require SIP Line Messaging Guide (Standard Edition) for Cisco Unified Communications Manager 9 SIP Standard Line Interface Standard Interface Compliance Summary