Unaffiliated Ericsson Australia Instant Messaging (IM) refers to the transfer of messages between users in real-time. This document provides a mechanism whereby endpoints can request Instant Message Disposition Notifications (IMDN), including delivery, processing, and display notifications, for page-mode instant messages. The Common Presence and Instant Messaging (CPIM) data format specified in RFC 3862 is extended with new header fields that enable endpoints to request IMDNs. A new message format is also defined to convey IMDNs. This document also describes how SIP entities behave using this extension. [STANDARDS-TRACK]