Hi, I'm receiving a voice calls that were forward to my telnyx number When the call get to livekit the caller is the original caller, not the forwarder - for example caller is X - calling to number Y, Y is forwarding the number to my telnyx number, in the call - the caller is X and Y not exists how can I know the forwarder number - Y in the example ?

Thanks for reaching out, Niv. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.

1. looking for the intermediate number 2. LiveKit Agent indeed, not sure about the transfer 3. Don't know

I understand you're looking to extract the intermediate forwarding number in SIP calls when using LiveKit Agents. While LiveKit doesn’t offer a direct way to get this information, it might still be accessible through SIP headers like

From

,

P-Asserted-Identity

, or

Diversion

, depending on how Telnyx handles forwarded calls. Here’s what I suggest you try next: • Reach out to Telnyx to see if they include these headers in forwarded calls. • Set up your SIP trunk in LiveKit to capture headers by using

headers_to_attributes

or

include_headers

. This can help you map the relevant SIP headers to participant attributes for easier tracking. If you’d like, I’m here to help you with configuring these SIP headers or if you have any other details to share, just let me know. We’ll work through this together! Sources: Preserving Caller ID During SIP Transfers in LiveKit Agents | sip-refer/agent.py | protobufs/livekit_sip.proto

Can you give me a code example of how to use the

headers_to_attributes or include_headers ?

I'd love to help you get comfortable with using

headers_to_attributes

and

include_headers

in your LiveKit SIP trunk configuration. Here’s a friendly walkthrough: 1. Using

headers_to_attributes

This lets you map specific SIP X-* headers to LiveKit participant attributes. For example:

{
  "headers_to_attributes": {
    "X-Custom-Id": "caller_id",
    "X-Tenant": "tenant_name",
    "X-Queue": "queue_id"
  }
}

With this setup, the

X-Custom-Id

header from the SIP INVITE is captured and added as a participant attribute called

caller_id

. Pretty neat, right? 2. Using

include_headers

This feature automatically maps SIP headers to

sip.h.*

participant attributes. Here’s how you can use it: • To auto-map all

X-*

headers:

{
  "include_headers": 1
}

• Or, to include all SIP headers:

{
  "include_headers": 2
}

3. Example API Request Here’s a sample Create SIP Inbound Trunk request to illustrate everything:

curl -X POST <https://your-livekit-url/twirp/livekit.SIP/CreateSIPInboundTrunk> \
-H "Authorization: Bearer <token>" \
-H 'Content-Type: application/json' \
-d '{
  "name": "My Inbound Trunk",
  "numbers": ["+15551234567"],
  "headers_to_attributes": {
    "X-User-ID": "user_id",
    "X-Dept": "department"
  },
  "include_headers": 1
}'

If you have any questions or want to explore this further, please don’t hesitate to reach out. I’m here to help you every step of the way! Sources: SIP APIs | LiveKit Docs | protobufs/livekit_sip.proto

Great, thanks, it works I added the headers to the sip trunk in the dashboard and it shows in the headers

You're very welcome! I'm so happy to hear that everything is working and the headers are showing up just as you wanted. If you ever have more questions or need a hand with anything else, please don't hesitate to get in touch. I'm here to help!