Hello there, my call transfera are not working anymore since lastweek. Can You help please? Call ID: 67132ecf-77d6-40d6-adab-ef6a0361d1f1

Hey, I’ve worked on call transfer issues in VAPI before — often it comes down to how the destination or arguments are being passed. Are you trying to transfer to one number or multiple?

Hi ITD, For troubleshooting call transfer issues, please ensure the following: 1. **Check Call Logs**: Verify the

endedReason

field by making a GET request to Vapi API (

GET https://api.vapi.ai/call/{call_id}

) with your credentials. If

endedReason

shows as

assistant-forwarded-call

, and calls still drop, the issue might be with the telephony provider [Debug call forwarding drops](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops). 2. **Verify Configuration**: Ensure the

phoneCallProviderBypassEnabled

is set to

false

and remove the

"phone-call-control"

from

serverMessages

in your configuration if you're not implementing custom call logic (see [Debugging Guidance](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops)). 3. **Transfer Compatibility**: Support only specific transfer paths, e.g., PSTN to phone number is supported, but web to phone is not ([Transfer scenario limitations](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops)). 4. **Telephony Provider Integration**: Analyze logs on your telephony provider's (like Twilio) dashboard using

phoneCallProviderId

for errors ([Help with Integrations](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops)). 5. **SIP Calls**: If using SIP, ensure the SIP packets include a

REFER

packet. Missing packets indicate Vapi didn't initiate the transfer (see [SIP Analysis](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops)). Review these settings and refer to the [Vapi Documentation](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops) for detailed guidance. If this doesn’t resolve the issue, please let us know and we’ll be happy to step in and assist further.

Hi Xcel, Im using multiple SIP:Uri Extensions, it was working before, but suddenly it stops working without any change from my side, Im using a logic within the assistant. I would appretiate any help a lot. Thank You

Hi I’ve handled similar SIP transfer cases where the issue was tied to phoneCallProviderBypassEnabled not being set properly or the assistant logic not passing the transfer arguments as expected. Since it was working before and stopped suddenly, I can help you dig into the exact flow and get this resolved directly. Would you like me to jump in and take a closer look with you? @ITD

Hi @Vercel , Thank you for your response, There is any way to set phoneCallProviderBypassEnabled to false to an existing Assistant? Best Regards

Hi ITD, you can update an existing assistant's settings via the API:

curl -X PATCH 'https://api.vapi.ai/assistant/{assistantId}' \-H 'Authorization: Bearer YOUR_API_KEY' \-H 'Content-Type: application/json' \--data-raw '{  "phoneCallProviderBypassEnabled": false}'

Key points: 1. Use a PATCH request to update only specific fields 2. Include the assistantId in the URL 3. Set phoneCallProviderBypassEnabled to false in the request body 4. Maintain other existing assistant settings The phoneCallProviderBypassEnabled setting: - When false: Uses standard telephony routing - When true: Bypasses normal provider routing - Can be modified on existing assistantsify the root of the transfer issues. For more information, please refer to the [Debug Call Forwarding Drops guide](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops). let us know if you need further assistance.

Hello, i tried this and got this error { "message": [ "property phoneCallProviderBypassEnabled should not exist" ], "error": "Bad Request", "statusCode": 400 } Can you help please?

Yes, I tried that and had the same error than Mish

Thank you for providing this information. We’ll be looking into it further to better understand the situation and determine the next steps. Our team will update you as soon as we have more details, and we truly appreciate your patience and cooperation in the meantime.

hey i am getting the same message, what did you do to set it to false, best regards @ITD

Im not being able to fix it yet

@User is youre call transfer dropping to? and where are you based

Hi, If your call is dropping during transfer, here are the key things to check and fix[1](https://docs.vapi.ai/phone-calling/transfer-calls/debug-forwarding-drops): 1. Check if Vapi successfully initiated the forwarding:

curl -X GET "https://api.vapi.ai/call/{call_id}"

Look for `endedReason`: If it shows "assistant-forwarded-call", Vapi forwarded successfully. 2. Verify your configuration: - Make sure

phoneCallProviderBypassEnabled

is set to

false

- Remove

"phone-call-control"

from

serverMessages

if present 3. Check your transfer scenario is supported: - Phone call → Phone number ✅ - Web call → Phone number ❌ (not supported) - Phone call → SIP number ❌ (PSTN to SIP not supported) - SIP call → Phone/SIP number ✅ 4. If calls still drop, check your telephony provider logs (Twilio, Vonage, Telnyx) using the

phoneCallProviderId

from the Vapi call response. Make sure your destination number includes country code and test calling it directly outside of Vapi to verify availability.

The call shows: "assistant-forwarded-call", and Im not being able to send this property through the VAPI API: Im getting this: { "message": [ "property phoneCallProviderBypassEnabled should not exist" ], "error": "Bad Request", "statusCode": 400 } This issue is from more than a month ago now, We need to have transfer calls, we are loosing potential clients because of this!!!

We are actively looking into this, can you try to: 1. First, remove the

phoneCallProviderBypassEnabled

property from your request - the error indicates this property should not be included in the API call. 2. Instead, verify these configurations: - Remove

"phone-call-control"

from

serverMessages

if present - Ensure your transfer function is properly configured - Check destination number format includes country code 3. For a standard Vapi forwarding setup, your configuration should look like:

{
  "assistant": {
    "serverMessages": [
      "status-update"
    ]
  }
}

4. When using the transfer call tool, use this format:

{
  "type": "transferCall",
  "destinations": [
    {
      "type": "number",
      "number": "+1234567890",
      "message": "Connecting you now..."
    }
  ]
}

Try removing the

phoneCallProviderBypassEnabled

property from your request and ensure your transfer destinations are properly formatted. If issues persist, check your telephony provider logs for transfer failures.