VAPI•7mo ago

SIP REFER Requests

SIP REFER Requests from Vapi aren’t being handled correctly.

Does Vapi’s device or software support REFER and handle NOTIFY messages?

Is the target device (192.76.120.10) capable of receiving REFER and completing transfer.

specific-silver•6/1/25, 8:24 PM

@Dan Are you trying to perform a SIP REFER on a BYO SIP Trunk? or via the VAPI connected Twilio/Telnyx numbers ?

wispy-yellowOP•6/1/25, 10:22 PM

@Nir S (CEO/Founder @Cloudonix) VAPI connected to Telnyx

specific-silver•6/1/25, 10:28 PM

Ok, just checking

unexpected-ivory•6/2/25, 3:37 AM

This is a major issue we are having as well. Waiting on support resolve issue.

Uunexpected-ivory This is a major issue we are having as well. Waiting on support resolve issue.

wispy-yellowOP•6/2/25, 6:23 AM

Any update on the issue?

KyleAPP•6/2/25, 1:00 PM

You need to enable the REFER permission from the Telynx team, and then send the SIP refer like this: sip:your-transfer-destination@sip.telynx.com.

Ccomprehensive-tomato You need to enable the REFER permission from the Telynx team, and then send the ...

wispy-yellowOP•6/2/25, 4:36 PM

SIP REFER has been enabled. Where exactly do I send the SIP destination under?

wispy-yellowOP•6/3/25, 3:53 PM

@Mark Is the issue fixed your end?

unexpected-ivory•6/3/25, 3:54 PM

There’s nothing on our end to fix. Vapi needs to process the INVITE properly like any other SIP endpoint and not manipulate the realm.

unexpected-ivory•6/3/25, 3:58 PM

We can’t be the only ones experiencing this issue…

Uunexpected-ivory There’s nothing on our end to fix. Vapi needs to process the INVITE properly lik...

dangerous-fuchsia•6/3/25, 7:16 PM

We are not manipulating any Realm here. In case you your confident, you can present the document to prove your point, I'll review it. If it's an issue on our side, we'll definitely fix it.

dangerous-fuchsia•6/3/25, 7:25 PM

@Dan For Vapi-Telnyx integration, SIP destinations need to be configured in the transfer tool destinations or assistant settings using the specific Telnyx SIP format: sip:your-transfer-destination@sip.telnyx.com

Configure your transfer destination in the Transfer Call Tool:

{
  "type": "transferCall",
  "destinations": [
    {
      "type": "sip",
      "sipUri": "sip:your-transfer-destination@sip.telnyx.com",
      "description": "Transfer to your endpoint",
      "transferPlan": {
        "mode": "blind-transfer",  // or other transfer modes
        "sipVerb": "refer"  // Uses SIP REFER (default)
      },
      "sipHeaders": {
        // Optional custom SIP headers
        "X-Custom-Header": "value"
      }
    }
  ]
}

{
  "type": "transferCall",
  "destinations": [
    {
      "type": "sip",
      "sipUri": "sip:your-transfer-destination@sip.telnyx.com",
      "description": "Transfer to your endpoint",
      "transferPlan": {
        "mode": "blind-transfer",  // or other transfer modes
        "sipVerb": "refer"  // Uses SIP REFER (default)
      },
      "sipHeaders": {
        // Optional custom SIP headers
        "X-Custom-Header": "value"
      }
    }
  ]
}

notesnotes
URI Format: Must be sip:destination@sip.telnyx.com
Domain: Always use sip.telnyx.com as the domain for Telnyx routing
Destination: Replace your-transfer-destination with your actual SIP endpoint identifier

Let me know if you require further help!!

Ddangerous-fuchsia We are not manipulating any Realm here. In case you your confident, you can pres...

unexpected-ivory•6/4/25, 4:36 AM

I provided it to Sagar today in a separate email. Please get with him. Thanks

Ddangerous-fuchsia @Dan For Vapi-Telnyx integration, SIP destinations need to be configured in the ...

wispy-yellowOP•6/4/25, 9:45 AM

Telnyx phone number’s connected for inbound calls. This is my configuration for call transfer for an external number.

Uunexpected-ivory I provided it to Sagar today in a separate email. Please get with him. Thanks

dangerous-fuchsia•6/5/25, 4:21 PM

Thanks.

{ "type": "transferCall", "destinations": [ { "type": "sip", "sipUri": "sip:your-transfer-destination@sip.telnyx.com", "description": "Transfer to your endpoint", "transferPlan": { "mode": "blind-transfer", // or other transfer modes "sipVerb": "refer" // Uses SIP REFER (default) }, "sipHeaders": { // Optional custom SIP headers "X-Custom-Header": "value" } } ] }

SIP REFER Requests

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