Sending custom headers from livekit but not receiving on Kamailio / sip server side , checking using sngrep tool ? how to fix that ?

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1. kamilio to livekit 2. BYE 3.

attributes_to_headers

4.

attrs = {
            "five9.route_type": "Queue",
            "five9.route_value": "Queue",
            "five9.queue": "True",
            "five9.iva_session_id": str(self.state.session_id or ""),
            "five9.person_id": str(self.state.person_id or ""),
            "five9.studio_contained": "No",
            "five9.language": self.state.language or "en-US",
            "five9.transfer_reason": str(reason or ""),
        }

5. dont know

Thanks — this is helpful. You’re sending BYE headers from LiveKit (Kamailio → LiveKit call direction, and LiveKit should send headers back on BYE) using

attributes_to_headers

, and you’ve shown the attributes you set. Let’s walk through targeted checks and next steps to find why Kamailio (sngrep) doesn’t see them. Quick checklist — verify these first 1. Ensure attributes are set on the SIP participant at hangup time ◦ Confirm your code sets those

attrs

on the participant before the call ends. Headers mapped by

attributes_to_headers

are emitted only if the participant still has those attributes when LiveKit generates the BYE. 1. Confirm mapping keys exactly match trunk config ◦ The attribute names you set (e.g.,

five9.route_type

) must match the keys in your trunk’s

attributes_to_headers

mapping exactly. Even small typos or different punctuation will prevent mapping. 1. Verify the trunk configuration maps each attribute to the desired SIP header ◦ Example mapping form:

"attributes_to_headers": {
       "five9.route_reason": "X-RouteReason",
       "five9.route_type": "X-RouteType",
       "five9.route_value": "X-RouteValue",
       "five9.metadata": "X-MetaData"
     }

• Confirm your trunk has the mappings for the exact attribute keys you use above (e.g.,

five9.queue

,

five9.iva_session_id

, etc.). 1. Capture the raw SIP message leaving LiveKit ◦ Capture at the LiveKit network edge (or from LiveKit logs) so you can confirm whether LiveKit included the X- headers in the BYE it sent. If the header is present there, the problem is downstream; if not, LiveKit didn’t include them. 1. Confirm no intermediary strips the headers ◦ If the headers are present leaving LiveKit but absent when Kamailio sees them, an SBC/proxy or carrier between LiveKit and Kamailio is likely removing unknown or X- headers. Many intermediaries drop custom headers by policy. Targeted troubleshooting steps 1. Reproduce a single call and do two captures: a. Capture at LiveKit egress (or retrieve LiveKit’s raw SIP for that BYE). b. Capture on the Kamailio interface (where you run sngrep). ◦ Compare the two captures. If BYE from LiveKit contains headers but Kamailio’s packet does not, the path in between is stripping them. 1. If LiveKit’s BYE does NOT include the headers: ◦ Re-check that you set the attributes on the specific SIP participant entity LiveKit uses for that call (participant vs. room metadata). ◦ Ensure attributes are set before the session ends (i.e., before LiveKit sends BYE). ◦ Verify your agent code uses the correct LiveKit API call (update_participant or equivalent) and that it returns success. 1. If headers are present on LiveKit egress but lost before Kamailio: ◦ Check any SBCs, proxies, load balancers, or carrier hops for header-stripping policies and allow forwarding of your header names (prefer

X-

prefixes). ◦ Try a direct connection (if possible) from LiveKit to Kamailio to confirm intermediaries are the cause. 1. Confirm header names on Kamailio side ◦ Kamailio expects headers with exact names. If your mapping uses

X-RouteReason

, search sngrep for that exact header name. ◦ Some SIP stacks treat header casing differently; search case-insensitively in captures. What would help me pinpoint the issue • A redacted snippet of the LiveKit egress BYE (raw SIP) or confirmation of whether LiveKit’s outgoing BYE contains the headers. • The trunk JSON snippet showing your

attributes_to_headers

mapping. • A redacted sngrep capture from Kamailio showing the BYE where headers are missing. If you want step-by-step capture commands, tell me whether you can run tcpdump on the LiveKit-side host and I’ll provide the exact tcpdump filter to capture SIP BYE traffic and the grep to look for your header names. Next suggested action • If you can, capture and paste (redact secrets) the raw BYE from LiveKit egress and the sngrep capture from Kamailio. I’ll compare them and tell you whether LiveKit sent the headers or if an intermediary removed them, and then give the exact fix.