Hey. I'm trying to use transfer tool, but when my agent says "transfering the call now" it hangs up on me immidiately after. The message is not even my message which i set up. Here is my code: { "id": "4ae0ef79-6496-4d5b-a748-cbbb2433d0a3", "createdAt": "2025-05-28T06:34:44.923Z", "updatedAt": "2025-05-28T06:58:14.375Z", "type": "transferCall", "function": { "name": "hivasatiranyitas", "parameters": { "type": "object", "properties": {}, "required": [] } }, "orgId": "6d09497e-c5f6-491a-8659-b01e81283d96", "destinations": [ { "type": "number", "number": "+36701234567", "message": "Átirányitom a hívást", "description": "Minden esetben ezt kell használni, ha a felhasználó az ügyfélszolgálattal akar beszélni.", "transferPlan": { "mode": "warm-transfer-say-message", "message": "Átirányitom a hívást", "sipVerb": "refer" }, "numberE164CheckEnabled": true } ] } What should i do to get the transfer correctly?

To fix your transfer tool, add the required

destination

parameter to your function definition:

json
"parameters": {
  "type": "object",
  "properties": {
    "destination": {
      "type": "string",
      "enum": ["+36701234567"],
      "description": "The destination to transfer the call to."
    }
  },
  "required": ["destination"]
}

Update your function with this, and your call transfer should work as expected. If you're using SIP trunking, also make sure SIP REFER is enabled with your provider. Sources: - [Vapi documentation: call forwarding](https://docs.vapi.ai/call-forwarding) - [Vapi SIP Trunking Telnyx external number call forwarding troubleshooting](https://discord.com/channels/1211482211119796234/1343963959421829172)

I have problems in transfer call, too.

To resolve your transfer call issue, update your function definition to include the required

destination

parameter as shown below:

json
"parameters": {
  "type": "object",
  "properties": {
    "destination": {
      "type": "string",
      "enum": ["+36701234567"],
      "description": "The destination to transfer the call to."
    }
  },
  "required": ["destination"]
}

Add this to your function, and your call transfer should work as expected. If you're using SIP trunking, also ensure SIP REFER is enabled with your provider. Sources: - [Vapi documentation: call forwarding](https://docs.vapi.ai/call-forwarding) - [Vapi SIP Trunking Telnyx external number call forwarding troubleshooting](https://discord.com/channels/1211482211119796234/1343963959421829172)

Can I use vapi free phone number to transfer call?

Vapi free phone numbers are designed for US national use and can place/receive calls, but the documentation does not explicitly confirm whether call transfers (using the transfer tool) are supported on free numbers. There are no stated restrictions, but also no guarantees. To be sure, try setting up a transfer with your free number and test the behavior, or contact Vapi support for confirmation. Sources: - [Vapi documentation: phone calling](https://docs.vapi.ai/phone-calling) - [Vapi documentation: call forwarding](https://docs.vapi.ai/call-forwarding)

Yes, it is possible to transfer a call with a Vapi free number. Could you provide a call id so we can investigate the logs?

having the same issue, call id - c68c8a8c-29d2-470d-9e07-8e47b5ee7d95

It looks like the main issue is that your function definition for the transfer tool is missing the required

destination

parameter. Updating your function parameters to include

"destination"

as shown below should help resolve the problem:

json
"parameters": {
  "type": "object",
  "properties": {
    "destination": {
      "type": "string",
      "enum": ["+36701234567"],
      "description": "The destination to transfer the call to."
    }
  },
  "required": ["destination"]
}

Once you add this, your call transfer should work as expected. If you're using SIP trunking, make sure SIP REFER is enabled with your provider. Let me know if you continue to experience issues after making this change! Sources: - [Vapi documentation: call forwarding](https://docs.vapi.ai/call-forwarding) - [Vapi SIP Trunking Telnyx external number call forwarding troubleshooting](https://discord.com/channels/1211482211119796234/1343963959421829172)

Hey, the call was forwarded successfully. Can you try a few more calls and let me know how it goes for you?

Hi Hi! So sorry for such a late response.. 53efdcc8-22f2-4cb5-814b-316bc24cf8b8 I tried testing again.. but it just hangs up the caller... even if the status states assistant forwarded the call. Also, I had setup a warm transfer but as I said - the call just drops

hey @sieze420 I moving your ticket to investigation status to take a look into it later.

Ok thanks! Will this take long?

Hey @DX4HAF , just wanted to confirm you are trying to transfer to an international number which is not based on the US or Canada. VAPI provided numbers can only forward and make calls to the US and Canada regions only.

Yeah we tried with US numbers as well. But still it didn't work. It works with a Twilio number but not vapi number

Could you please provide a call id where you are trying to transfer from a VAPI US number to another US number?