Which protocol primarily facilitates communication between Avaya endpoints and Communication Manager?

The protocol that primarily facilitates communication between Avaya endpoints and Communication Manager is H.323. This protocol is part of a suite of standards that enable voice, video, and data communication over packet-switched networks, making it particularly suitable for multimedia conferencing.

H.323 is pivotal in the context of Avaya's architecture because it integrates signaling and media transport capabilities necessary for establishing and managing communication sessions. It supports a range of features such as call control, media transport, and bandwidth management, which are essential for a seamless communication experience across different types of endpoints.

While other protocols like SIP (Session Initiation Protocol) have become more prevalent in recent years due to their simplicity and versatility, H.323 remains a critical component of the Avaya ecosystem, especially for legacy systems and certain configurations within Avaya Aura environments. Its robust framework accommodates real-time communication, making it a fundamental choice for institutions relying on Avaya technology to facilitate their communications infrastructure.