Voice Agents HandBook

Build voice agents that pick up real phone calls, answer in under a second, and don't fall over when ten people call at once.

A 100-page handbook for backend developers who got handed the brief "add voice to our product" and need to ship not in six months, in three weekends.

If you've ever opened the LiveKit docs and tried to assemble a working agent from forty-seven Discord threads, you know how the weekend goes. The pipeline almost works. The agent talks over the user. The phone integration silently drops every other call. The deploy script assumes a Kubernetes cluster you don't have. Voice Agents Handbook collapses those weekends into one read.

You'll start at a thirty-line agent in Chapter 2 and end with a voice agent answering real calls for a real business a phone number, a web button, a mobile feature, and a deployment shape that does not crash under load. Every chapter pays its way against the 800ms budget that decides whether a voice agent feels real or feels broken.

Inside, you'll build and learn:

• A working voice agent in about fifty lines, running locally on your machine
• The five-component pipeline (VAD, STT, turn detection, LLM, TTS) that every production voice agent uses, and the latency budget that makes it feel alive
• System prompts that sound human spoken aloud, not robotic the rules that flip the moment audio replaces text
• Function tools that let agents look things up, book appointments, and call APIs mid-conversation
• Agent handoffs and multi-step flows for the moments when one agent isn't enough
• Latency, interruptions, and turn-taking the timing problems that separate a demo from a conversation
• Phone, browser, and mobile surfaces what changes between them and what stays the same
• The patterns that ship in production: receptionists, triage and handoff, outbound callers, IVR replacements
• Testing with synthetic callers so you find the bug before your first real user does
• Deployment and observability for the night something breaks at 2 AM

Nine chapters across three parts, written to be read in a weekend and kept open next to your editor for years. No padding, no demo-grade examples that fall apart in production, no "now deploy this to Kubernetes" hand-waving in the final chapter. Every code example is complete and runnable as printed. Every architectural claim has a number behind it.

Written by Mahimai Raja, a voice AI engineer who has built and shipped production voice agents on LiveKit for clients in Canada, Switzerland, and Australia. He contributes to the LiveKit Agents open source project and runs the Voice AI Community on LinkedIn. This is the field guide he wishes existed when he started.

Prerequisites: Python 3.11+, comfort with async/await, a rough sense of what STT, LLM, and TTS do. Prior LiveKit experience is not assumed.

Stop assembling voice agents from Discord threads. Ship one.