Introduction: From Voice AI Prototype to Production Phone AgentA voice AI demo is a model, a microphone, and a speaker. A phone agent is a distributed system. Audio arrives from a carrier over a SIP trunk, callers interrupt on bad lines, backends time out, model providers have bad minutes, and callers want a person the moment something goes wrong.This article shows you how to build an AI receptionist for a dental clinic. It answers calls to the clinic’s number, looks up patients by caller ID, looks up and books appointments through a backend API, and transfers calls to the front desk when a person is needed. It runs on LiveKit Agents, the open-source framework for Python and Node.js. The logs highlight which features require LiveKit Cloud. Every snippet comes from one working project, and every output shows what that project printed.