### Answer The

error_no_audio_received

disconnection reason indicates that Retell has not received audio from the frontend for a while after the connection was established. [(1) ]() Here are some troubleshooting steps: 1. Check for client-side audio issues - Ensure your browser has microphone permissions enabled - Try a different browser (Chrome is recommended) - Restart your computer to clear any audio device conflicts [(2) ]() *2. Verify your WebSocket connection (if using Custom LLM) * - Test your WebSocket URL endpoint using Postman to verify the connection is established [(3) ]() - Ensure your URL protocol matches your connection type: - HTTPS endpoints: Use

wss://

prefix - HTTP endpoints: Use

ws://

prefix - Check for trailing slashes in your URL that might cause issues 3. Add logging to diagnose the issue - Add logging in your WebSocket code to confirm the connection is established - Add logging in your WebSocket message handler to verify you're receiving messages from the Retell server 4. Check your server setup - Verify your server supports WebSocket connections—some platforms like Vercel edge functions and serverless functions cannot act as a WebSocket server If the issue persists after these checks, it may be a platform-side issue that requires support investigation. You can create a thread in the bug-report channel with your call ID and detailed logs for the team to review. [(4) ]()

​ To learn more, see the sources I considered: [[1] Debug call disconnection](https://docs.retellai.com/reliability/debug-call-disconnect) [[2] Unable to Test Audio](https://discord.com/channels/1186424376300679209/1434324910146191511) [[3] Troubleshooting Guide](https://docs.retellai.com/integrate-llm/troubleshooting) [[4] Discord message from @0xluffyb on 2025-03-11](https://discord.com/channels/1186424376300679209/1186462578310910112/1349127713436205087) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.