Glossary

H.245 is an ITU-T standard that defines a control protocol for multimedia communication.

H.245 passes its control information messages over a reliable channel between two entities that are engaged in a multimedia call (voice only or voice and video). H.245 messages are defined using ASN.1 and are encoded using PER.

H.245 starts with a capabilties exchange procedure which enables participants in the session to understand what are the capabilities of the other entity in the call and operate under this information by opening the relevant multimedia channels.

H.245 is used as the control channel by both H.323 and the 3G-324M standards.

In the scope of H.323, H.245 uses its own TCP session between the entities or is tunnelled over Q.931 messages.

In the scope of 3G-324M, H.245 is allocated to predefined logical channel and is carried over xSRP, providing it a reliable channel.