I’ve seen this issue before with Vapi transfers. The problem usually comes down to how the system is reading the assistant reference, and there are a few key differences between using IDs, names, or squads for routing. I can help you sort out which one works best for your setup so the transfers go through without errors. @alireza

Hi alireza, To set up and use the transferCall function to forward calls to different numbers, follow these steps: 1. **Create a Transfer Call Tool in the Vapi Dashboard**: - Go to the Tools section in your Vapi dashboard. - Click on "Create Tool" and select "Transfer Call" as the tool type. - Configure your destinations with corresponding messages. For example: - Department A: +1234567890 - Department B: +0987654321 2. **API Configuration**: - You can also define the tool via API:

json
     {
       "tools": [
         {
           "type": "transferCall",
           "destinations": [
             {
               "type": "number",
               "number": "+1234567890",
               "message": "I am forwarding your call to Department A. Please stay on the line."
             }
           ],
           "function": {
             "name": "transferCall",
             "parameters": {
               "destination": "+1234567890"
             }
           }
         }
       ]
     }

3. **Warm Transfer Options**: To implement a warm transfer, configure your transfer plan based on your needs: - Warm Transfer with Summary: Set the mode to

"warm-transfer-with-summary"

. - Warm Transfer with Message: Set the mode to

"warm-transfer-with-message"

. For detailed guidance on setting up these options, please refer to the [Call Forwarding Documentation](https://docs.vapi.ai/call-forwarding). Make sure to test the configuration to confirm it's working correctly. If you encounter issues, checking the logs for errors might provide further insights.