Field notes
One note per failure: the symptom the way you would search for it, the mechanism underneath, the checks that confirm it, and what I changed or would change. They come out of LiveKit Agents, WebRTC media, SIP and PSTN, the infrastructure below them, and the harness that proves a fix held.
Infrastructure
After a reboot or container recreate, outbound dialling fails silently. How to persist Redis state, configure systemd, and self-heal stale trunk identifiers.
A host reboot leaves your media server healthy and browser calls working, but phone calls silently fail until someone provisions SIP trunks by hand.
SIP and PSTN
Fix the missing first word on outbound AI phone calls by gating your greeting on audio track subscription, not the SIP participant active signal.
Echo-cancellation warm-up defaults erase the first word of a telephony answer. Learn how to tune SIP transport boundaries to prevent empty first turns.