Summary

This Recommendation specifies syntax and semantics of terminal information messages as well as procedures to use them for in-band negotiation at the start of or during communication. The messages cover receiving and transmitting capabilities as well as mode preference from the receiving end, logical channel signalling, and Control & Indication. Acknowledged signalling procedures are specified to ensure reliable audiovisual and data communication.

Relative to Version 10 (2003-07) of H.245, this version includes:

•            support for RFC 3389 – RTP Payload for Comfort Noise;

•            support for bit rates in multiple payload stream;

•            L16 Capability Definition;

•            resolution of H.245 Open Logical Channel Conflicts;

•            definition of a minimum audio packet rate;

•            ITU-T Rec. H.235 Annex G "Usage of the MIKEY key management protocol for the secure real time transport protocol (SRTP) within H.235";

•            compact H.245 Capabilities Expressions;

•            generic capability for Nx64K Circuit Relay over IP;

•            update of Resolution of H.245 Open Logical Channel Conflicts;

•            call reset procedure in ITU-T Rec. H.324.

Products claiming compliance with Version 11 of H.245 shall comply with all of the mandatory requirements of this Recommendation. Version 11 products can be identified by H.245 TerminalCapabilitySet messages containing a protocolIdentifier value of {itu-t (0) recommendation (0) h (8) 245 version (0) 11}.