Thanks — I see you're hitting this TwirpError (code: canceled, status: 408) when creating a SIP participant for an outbound call. That error means the server-side SIP transaction timed out (transaction failed to complete / 0 intermediate responses). What this usually indicates • The outbound SIP INVITE did not complete before the server's timeout. • Common causes: unreachable or misconfigured SIP trunk, the SIP provider not responding to INVITES, network/firewall issues between LiveKit and your provider, or using

wait_until_answered=true

and the call never being answered in time. To help diagnose and fix this, please share: 1. The code snippet or API call you use to create the SIP participant (include parameters like

wait_until_answered

). 2. Whether

wait_until_answered

is set to

true

. 3. The region your LiveKit instance is hosted in. 4. Any recent changes to your SIP trunk configuration (SIP server IPs, credentials, codecs, TLS/SRTP settings). 5. Provider-side SIP logs (INVITE, 1xx/2xx/3xx/4xx responses) if available. 6. Any network/firewall rules or NAT between LiveKit and the SIP provider. Quick troubleshooting steps you can try now • Try the same call with

wait_until_answered=false

to confirm the timeout is tied to waiting for an answer. • Verify the SIP trunk is reachable from your LiveKit host (SIP INVITE can be proxied/tested from the same network). • Confirm codecs and transport (UDP/TCP/TLS) match what the provider expects. • Check for dropped packets or high latency between LiveKit and the provider. Send the requested details and any SIP traces you can, and I’ll help pinpoint the cause and next steps. Sources: Agents telephony integration | LiveKit docs | Outbound Calling Script | LiveKit docs