# Custom SIP headers not appearing in participant attributes

**URL:** <https://community.livekit.io/t/custom-sip-headers-not-appearing-in-participant-attributes/153>\
**Category:** Telephony\
**Tags:** sip-twilio, sip-trunking\
**Created:** [January 21, 2026, 1:35pm UTC](https://community.livekit.io/t/custom-sip-headers-not-appearing-in-participant-attributes/153 "2026-01-21T13:35:26Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![LiveKit-Community](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/livekit-community/32/67_2.png) [@LiveKit-Community](https://community.livekit.io/u/LiveKit-Community)\
**Post date:** [January 21, 2026, 1:35pm UTC](https://community.livekit.io/t/custom-sip-headers-not-appearing-in-participant-attributes/153/1 "2026-01-21T13:35:26Z")

</div>

_This question originally came up in our Slack community and the thread has been consolidated here for long-term reference._

I’ve configured my outbound trunk with `attributesToHeaders` to pass custom SIP headers, but I can’t see them in the call logs or participant attributes.

The configuration:

```json
{
  "headersToAttributes": {
    "xCompanyId": "company_id"
  },
  "attributesToHeaders": {
    "companyId": "X-CompanyId"
  },
  "includeHeaders": "SIP_ALL_HEADERS"
}

```

Is there something I’m missing?

---

<div class="post-metadata">

**Author:** ![LiveKit-Community](https://sea1.discourse-cdn.com/flex001/user_avatar/community.livekit.io/livekit-community/32/67_2.png) [@LiveKit-Community](https://community.livekit.io/u/LiveKit-Community)\
**Post date:** [January 21, 2026, 1:35pm UTC](https://community.livekit.io/t/custom-sip-headers-not-appearing-in-participant-attributes/153/2 "2026-01-21T13:35:29Z")

</div>

For outbound calls, passing custom SIP headers works by including them directly in the `CreateSIPParticipantRequest` headers field.

The trunk-level `attributesToHeaders` may not work as expected due to a known issue:

> <https://github.com/livekit/sip/issues/358>
>
> Hello, I am able to make calls in to LLM agent without issue. The livekit ecosys…tem is really great. However, I am having a problem passing the INVITE headers along to the participant attributes.
> 
> inbound-trunk.json
> \`
> {
> "trunk": {
> "include\_headers": 2,
> "headers\_to\_attributes: {
> "X-Test": "xTest"
> },
> "name": "{REDACTED} inbound trunk",
> "numbers": \["+1{REDACTED}"\]
> }
> }
> \`
> 
> I have tested using the v1.0.0 tag of the SIP service and v1.8.4 of livekit-server. I have tried various permutations and combinations of include\_headers values along with or without headers\_to\_attributes and attributes\_to\_headers. I have used the python SDK as well as the lk-cIi to create the inbound trunk. I apologize if I am missing something or have something misconfigured. Any suggestions on how to get this working or is this feature not yet implemented?
> 
> Thanks

Pass the headers manually in the CreateSIPParticipantRequest to work around this.