The Session Initiation Protocol (SIP) "Replaces" Header

This document defines a new header for use with Session Initiation Protocol (SIP) multi-party applications and call control. The Replaces header is used to logically replace an existing SIP dialog with a new SIP dialog. This primitive can be used to enable a variety of features, for example: "Attended Transfer" and "Call Pickup". Note that the definition of these example features is non-normative.