I need help to route the call to extension. I have created a tool from call transfer,

{
  "id": "d49493d4...",
  "createdAt": "....",
  "updatedAt": "...",
  "type": "transferCall",
  "function": {
    "name": "BNBA-Call-Transfer",
    "description": "This tool transfers the call to right extension according to user demand.",
    "parameters": {
      "type": "object",
      "properties": {},
      "required": []
    }
  },
  "messages": [
    {
      "type": "request-start",
      "content": "Please hold on while your call is transferring",
      "blocking": false
    },
    {
      "role": "assistant",
      "type": "request-complete",
      "content": "Thanks for your wait.",
      "endCallAfterSpokenEnabled": false
    }
  ],
  "orgId": "383c269a-c75a-484d-bd5f-6443188a3f6f",
  "destinations": [
    {
      "type": "number",
      "number": "+15089795557",
      "message": "",
      "callerId": "{{customer.number}}",
      "extension": "20193",
      "description": "Medical Records Requests"",
      "transferPlan": {
        "mode": "blind-transfer",
        "sipVerb": "refer"
      },
      "numberE164CheckEnabled": true
    }
  ]
}

These are the call logs for the tool call. Call is transferred to main number, but not redirects to the extension.

{
  "role": "tool_calls",
  "time": 1746103383632,
  "message": "",
  "toolCalls": [
    {
      "id": "call_j23ixoEjH1qgEptruV8if5kE",
      "type": "function",
      "function": {
        "name": "BNBA-Call-Transfer",
        "arguments": "{\n  \"destinations\": [\n    {\n      \"type\": \"number\",\n      \"number\": \"+15089795557\",\n      \"extension\": \"20210\",\n      \"message\": \"I am forwarding your call to Scott Arno's department. Please stay with us.\"\n    }\n  ]\n}"
      }
    }
  ],
  "secondsFromStart": 42.899
}

#1211483291191083018

Based on the information you've shared, I can see that your call is being transferred to the main number but not to the extension. This could be due to several factors. What type of PBX system are you using with Vapi? This is important because some PBX systems (like Yeastar) may not handle SIP REFER correctly when using "blind-transfer" mode, which could explain why the extension redirection isn't working.

I am not sure, how to check it the PBX system ?

@sakiboy Based on what you're showing - I don't think this will work. The way VAPI performs transfers is using a

SIP REFER

which is currently formatted to a manner that works with Twilio. If you're using an on-premise PBX system, there is a good chance that

SIP REFER

isn't supported (95% of systems don't support it). However, you can use Cloudonix as an in-between that will provide a similar capability, with a slight twist. DM me if you'd like to learn more.

Hey Sakiboy, checking if there are any doubts post our discussion in DMs.