Oracle There is a need for having a globally unique session identifier for the same SIP session that can be consistently maintained across SIP Proxies, Back-to-Back User Agents (B2BUAs), and other SIP middleboxes, for the purpose of troubleshooting. This document proposes a new SIP header to carry such a value: Session-ID. The mechanism defined in this document has been widely deployed, and is being followed in a backward-compatible fashion for a new Standards Track document produced by the INSIPID Working Group.