H.245 is used for what aspects of an H.323 session?

H.245 is specifically designated for capabilities exchange in an H.323 session. This protocol is essential for communicating the media capabilities of connected endpoints, allowing each participant to understand what media types they can support, such as audio and video formats, and how they can negotiate those capabilities to establish a session. It ensures that both ends of a communication link are compatible, facilitating seamless interaction during a call or conference.

In the context of H.323, the capabilities exchange process through H.245 allows for an agreement on codec usage, which is crucial for ensuring quality and compatibility in voice and video communication. This negotiation occurs after the session initiation takes place, allowing the endpoints to communicate their capabilities effectively.

Understanding this function of H.245 highlights its importance in establishing a successful multimedia communication session within the H.323 framework, further underscoring its role in the overall call setup process.