Thanks — I can help troubleshoot why agents sometimes take ~30s to join after a caller reaches your Twilio number. I’ll outline the most likely causes, give practical steps you can try right away, and ask a few quick questions that will help narrow the root cause. What I’m responding to: the random 30s delays between a Twilio call arriving and an agent actually joining the LiveKit room. Most likely causes • Worker availability / scaling: If your agent workers are limited (or a single replica), incoming jobs can wait for a worker to become available or reconnect. This is a common cause of intermittent long waits. • Agent cold starts / initialization: Agents run in a dedicated worker process. If that process needs to start, load models, or make external calls (STT/LLM/TTS) before joining, you can see long, variable startup times. • Dispatch / SIP routing delay: If your SIP/dispatch rules aren’t matching or there’s an intermediate routing delay, the call may not be dispatched to the agent immediately. • External AI or network latency: Any STT/LLM/TTS or other API calls the agent performs during startup add to join time—these services can be variable. • Observability gap: Without timestamps and logs for dispatch → room creation → agent join, it’s hard to know which stage is slow. Immediate troubleshooting steps (do these first) 1. Confirm worker replicas ◦ Ensure you have multiple agent workers (3+ recommended for redundancy) running with the same agent name to avoid single-point delays. 1. Add quick timestamps to logs ◦ Log timestamps for: Twilio webhook received, dispatch sent, room created (if you create it), worker job received, agent connect started, and agent joined. This will show where the delay happens. 1. Reproduce and note where delay occurs ◦ Is the delay before any agent logs appear? (dispatch/scaling issue) ◦ Or do logs show the agent started but finished initialization slowly? (initialization/third-party delay) 1. Check dispatch config / SIP rules ◦ Confirm your dispatch rule explicitly targets the agent via

room_config.agents

and that Twilio’s webhook/TwiML reaches your dispatch endpoint quickly. 1. Measure external service latencies ◦ If your agent calls STT/LLM/TTS at startup, instrument those requests to see if any provider calls are slow or timing out. 1. Prewarm / reduce cold starts ◦ If applicable, keep a warm worker pool or pre-initialize models (preload STT/VAD/TTS) before call traffic arrives. 1. Use fallback/retry logic ◦ Add timeouts and fallback adapters so a transient LLM/STT timeout doesn’t block joining. 1. Use Agent Observability and metrics ◦ Capture TTFT/TTFB and other session metrics to identify repeated patterns and correlating events. Targeted questions to help isolate the issue • Do you run agent workers yourself (self-hosted) or use LiveKit Cloud-managed agents? • How many agent worker replicas are running for this agent name? • When a delay happens, do you see any logs from the agent worker for that session? If yes, where do the logs show the pause (before receiving the job, during init, waiting on an external call, etc.)? • Do your agents call STT/LLM/TTS during initial join? If so, which providers do they use? • Is the delay consistent only at certain times of day or totally random? • Do you create rooms dynamically on call, or rely on auto-created rooms by dispatch? What I can do next for you • If you tell me whether workers are self-hosted vs managed and whether you have logs/timestamps from a delayed session, I’ll suggest precise checks and configuration changes (for example, scaling settings to add replicas, code snippets to add timing logs, or where to look in dispatch config). • If you can share a short timeline from logs (timestamps for Twilio webhook → dispatch → agent logs → agent joined), I’ll point straight to the problematic stage and recommend the exact fix. If you prefer, start by pasting: • Worker setup (self-hosted or cloud), and replica count • A single delayed session’s log timestamps around the call and agent join I’ll review and give step-by-step actions to remove the random 30s waits. Sources: Agents Framework | livekit/livekit_composite | DeepWiki | Agent dispatch | LiveKit Documentation | Voice Agent Architecture: STT, LLM, and TTS Pipelines Explained | LiveKit | Introducing LiveKit Inference: A unified model interface for voice AI | Liv... | SIP Lifecycle Management Agent | LiveKit Documentation, with interactive elements