Build a Voice Receptionist for Your Business · 25 min · Vapi

Voice AI Architecture + Vapi Overview

Every extra 200ms in the pipeline is 200ms of dead air a real caller notices -- latency isn't a nice-to-have in voice, it's the difference between natural and obviously robotic.

Hiring signal: Voice AI is the fastest-growing AI category for SMB automation -- understanding the full STT/LLM/TTS pipeline (not just calling an API) is what lets you actually debug and customize a voice agent instead of being stuck with a vendor's defaults.

What you will learn

Explain the voice pipeline (phone -> STT -> LLM -> TTS -> phone) and where latency accumulates
Understand Vapi's role as the orchestration layer across STT/LLM/TTS providers
Make a first test call to a basic assistant and verify the pipeline works end to end

Introduction

By the end of this course you'll call a real phone number and a receptionist you built will answer, qualify you, check real calendar availability, book you in, and text you a confirmation. Today: the pipeline underneath any of that, and a first call that proves it works.

What You're Building

A basic Vapi assistant configuration and one real test call — no custom voice, no conversation design, no tools yet. Today's entire job is understanding what happens between someone dialing a number and hearing a response.

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers The pipeline, and where latency actually comes from, Your first assistant, and a real call, What you're building today — plus a hands-on lab, quiz, and project artifact.

Create a free account to unlock Phase 0 and Phase 1 of every course — no credit card.