Thanks — I’m looking at the SIP error you reported: "unexpected status from INVITE response: sip status: 503: Service Unavailable." I can help troubleshoot, but I need a bit more context to give a precise diagnosis and steps to fix it. A 503 Service Unavailable from an INVITE generally means the SIP destination couldn’t accept the call right now. Common causes include overloaded or down SIP endpoints, networking/firewall issues, or an intermediary gateway (SIP trunk or SBC) returning 503. To narrow this down, can you tell me: • Which LiveKit component or external system returned the error? (For example: your SIP gateway/SBC, a SIP trunk provider, or a LiveKit SIP integration.) • When did you see this error? Is it happening for all calls or intermittently? • Any recent changes made to SIP configuration, DNS, certificates, firewall/NAT rules, or your SIP provider settings? • Do you have SIP logs or a full INVITE/response exchange (headers and timestamps)? If so, please paste the INVITE and the 503 response (sanitize any sensitive tokens). • Are other SIP calls to the same destination working from different clients or networks? • Are you using TLS or UDP/TCP for SIP transport, and is SRTP required for media? What I can do once you share those details: • Point to the most likely root cause (endpoint down, capacity, routing, TLS/certificate mismatch, NAT/firewall blocking) and specific checks to run. • Give step-by-step checks to run (reachability, SIP OPTIONS, retry behavior) and sample commands you can run (e.g., sipp, curl for health checks, or packet capture suggestions). • Help interpret SIP logs or the INVITE/503 exchange you paste here. If you prefer, start by sharing the INVITE + 503 response and whether this happens for all calls — that often lets me pinpoint whether it’s a server-side availability issue, an intermediary returning 503, or a client/transport problem. , with interactive elements