Build a Voice Receptionist for Your Business · 20 min · ElevenLabs · Vapi

Custom Voice with ElevenLabs

The default voice is the first thing that makes a caller think 'I'm talking to a bot' -- a well-chosen voice is the cheapest, highest-leverage upgrade in this whole course.

Hiring signal: Voice selection and tuning is a real, non-obvious skill -- most builders skip past it and ship the default, which is exactly why a well-voiced assistant stands out immediately.

What you will learn

Browse and select a professional voice from ElevenLabs' library
Configure voice settings (stability, similarity, style) and understand their tradeoffs
Connect the chosen voice to Vapi and verify quality with a real call

What You're Building

Replace the default voice from Lesson 1 with a real, chosen ElevenLabs voice — tuned, not just picked at random — and prove the difference by calling both back to back.

Voice settings aren't decoration — they change how natural it sounds

{
  "voice": {
    "provider": "11labs",
    "voiceId": "your-chosen-voice-id",
    "stability": 0.5,
    "similarityBoost": 0.75,
    "style": 0.3
  }
}

stability controls how consistent the voice sounds across a conversation (higher = more consistent but can sound flatter; lower = more expressive but can sound erratic). similarityBoost controls how closely the output matches the original voice sample (relevant mainly for cloned voices). style adds expressiveness/emotion at some cost to stability. There's no universally correct setting -- a receptionist wants consistency and clarity over dramatic expressiveness, which is a real, deliberate choice among these tradeoffs, not a default to accept blindly.

More expressive settings can add latency
Higher style values and more complex voice models can take marginally longer to generate per response -- in a domain where Lesson 1 already established that every hop's latency matters, a slightly more "flat but fast" voice setting can genuinely be the right tradeoff for a business phone line, even though it sounds less impressive in isolated testing.

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers Compare, don't just pick once and move on, 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.