When two-way audio is silent, first confirm the device actually supports it, then verify stage by stage.

1. Does the model support it? Many cameras are listen-only, with neither a built-in speaker nor an audio output for an external one. Check the specification or add a powered speaker.
2. Are the audio channels enabled? In the audio/video settings, confirm both input and output are switched on and use a codec both ends support — G.711A is the safest choice.
3. Client audio permissions: the mobile app needs microphone permission; the PC client or browser needs access to the audio device, and the system must not be routing output elsewhere.
4. Network and latency: intercom is latency-sensitive. Insufficient upstream bandwidth or a cross-network path produces choppy audio, so lower the intercom bitrate.
5. Echo and feedback: a speaker too close to the microphone howls. Enable echo suppression or adjust the relative position and level.

To test, verify intercom on the LAN with a client first, then over the internet. That quickly separates a device problem from a network one.