Troubleshooting Guide

Diagnose and fix common issues with Custom LLM WebSocket integrations.

Problem: Cannot Hear Audio After Entering Your WebSocket URL

Step 1: Test connection with Postman

1. Open Postman

   Create a new WebSocket request.

2. Connect

   Enter your WebSocket URL and click Connect.

3. Send a test message

   Navigate to the Message tab, enter “Hello”, and click Send. You should receive the message back in your server.

Step 2: Verify endpoint protocol

Endpoint type	URL prefix
HTTPS	wss://
HTTP	ws://

Step 3: Check for trailing slash

Some server setups don’t allow a trailing slash in the URL.

• ✅ Correct: https://example.com/websocket
• ❌ Incorrect: https://example.com/websocket/

Step 4: Check for server response

• Add logging in your WebSocket code to verify the connection is established
• Add logging in your message handler to confirm messages are received from UponAI

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Problem: Call Always Disconnects After a Few Seconds

• Add logging to check if you’re sending end_call: true unintentionally anywhere in your code
• Verify your server setup supports persistent WebSocket connections — Vercel edge functions and serverless functions cannot act as WebSocket servers

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Problem: Call Disconnects After 5–10 Minutes

Check your server vendor for automatic timeout settings. For example, Replit non-reserved instances time out at 5 minutes.