What is essential for establishing an H.323 trunk with Avaya Aura Communication Manager?

To establish an H.323 trunk with Avaya Aura Communication Manager, it is essential to configure both trunk groups and signaling groups correctly. The signaling group is responsible for managing call signaling between two endpoints, utilizing the H.323 protocol. This setup is crucial as it dictates how calls are initiated, maintained, and terminated over the trunk.

Additionally, the trunk group encompasses the physical or logical connections that facilitate the communication. Proper configuration of the trunk group determines the characteristics of the call, including routing and the maximum number of simultaneous calls. Therefore, both components work in tandem to ensure that the H.323 trunk functions as intended, allowing for seamless voice communication between systems.

The other options do not account for the necessity of both configurations. Simply having a signaling group (first option) would lack the physical connection needed for call establishment. Automatic configuration of H.323 trunks (third option) does not exist, as manual setup is required. Lastly, the requirement of only a SIP signaling group (fourth option) is incorrect since it specifically pertains to SIP protocol, while the question focuses on H.323 trunks.