If experiencing audio issues between internal local extensions, what should be checked first?

When experiencing audio issues between internal local extensions, it is essential to inspect the firewall checker test results first because firewalls can significantly impact VoIP communication, even for local extensions. A misconfigured firewall may block necessary traffic or impose restrictions that could interfere with the audio stream.

VoIP systems like 3CX rely heavily on real-time communication protocols, and if any part of the network, including firewalls, is not set up correctly, it can lead to audio problems such as one-way audio, dropped calls, or complete lack of audio. Running the firewall checker provides a diagnostic view of whether the setup is optimized for handling the VoIP traffic effectively.

While other factors like firmware updates or configuration settings may play a role in audio issues, the primary concern with local extensions is ensuring that the internal network's routing and access permissions are functioning correctly, which the firewall settings directly affect.