Which protocol does Cisco Unified IM and Presence use to exchange phone presence information with Cisco Unified Communications Manager?

XMPP is the protocol used between Jabber clients and the IM and Presence server for instant messaging and client-facing presence, not for the internal phone state exchange with CUCM.

CTI-QBE is a Cisco-proprietary CTI protocol used by contact center applications such as Finesse for call control actions, not for phone presence subscription between IM&P and CUCM.

IM and Presence subscribes to phone line state events on CUCM using the SIP event notification framework defined in RFC 3265, where CUCM sends NOTIFY messages whenever a monitored line transitions between idle, active, or ringing states. This SIP-based mechanism allows IM and Presence to aggregate phone status and surface it to Jabber clients alongside instant messaging availability. The integration relies on SIP specifically because CUCM exposes phone presence via a SIP presence server interface.

WebDAV is a file and calendaring extension of HTTP used in some unified messaging integrations and has no role in phone presence signaling.

HTTPS is a transport layer used for administrative APIs and web-based access and is not the protocol that carries phone presence subscription or notification events.

IMPP is an older IETF presence protocol that is not used in the IM and Presence to CUCM phone state integration.