I built the same AI receptionist on six AI voice agent platforms — Retell, Vapi, ElevenLabs, LiveKit, Bland and Telnyx — fed all six a byte-identical phone call, and measured speed, interruptions, setup, understanding, naturalness and cost. Here is what actually won, and which one is right for you.
16 min · The AI How · test date 2026-08-04 · same prompt, same recorded caller, one real tool call, defaults everywhere
| Platform | Score | Best for |
|---|---|---|
| Retell | 78 | Best overall |
| Vapi | 76 | Fastest setup + outbound |
| ElevenLabs | 73 | Fastest response |
| LiveKit | 72 | Total control |
| Telnyx | 64 | Telephony-native |
| Bland | 47 | Proprietary stack |
Scores are the weighted total across the six tests, from weights locked before any call ran. Full numbers and sources are in the public sheet.
Owning its own transcriber and voice gives ElevenLabs the lowest response time. Retell came second and posts the highest reliability of the six. Vapi has the tightest worst-case tail.
No independent benchmark exists, so we scored who shipped a named turn-detection feature this year. LiveKit (adaptive interruption + dynamic endpointing), Deepgram and OpenAI did. Most others have not, or have not said so.
Vapi's Composer wires the number, tools and agent from a single sentence. ElevenLabs is close on the cleanest dashboard. Retell sits in config and API docs. LiveKit is weeks, not hours.
On most platforms the transcriber is swappable, so word-error-rate is your config, not the platform's ceiling. ElevenLabs and Bland are fixed. Retell's transcriber swap is unconfirmed — ask before you commit.
A blind, loudness-normalized panel scored five dimensions. But a swappable voice one point lower today beats a locked voice that sounds good right now. Bland and ElevenLabs are the locked ones.
A real inbound minute is about 10.5 cents all-in (STT + LLM + TTS + telephony + platform fee), matched by an independent consultancy median. LiveKit is cheapest raw at a cent a minute; Retell wins on pricing clarity — every add-on published with a price.
No config? Vapi Composer. Want to see your real bill? Retell.
And it is not close, because HIPAA is included rather than a $24k/year add-on.
Retell for workspace separation and included concurrency, or Vapi if clients need serious outbound.
A cent a minute, total control, and every problem is now yours.
Granular billing — but re-read the legal section, your real constraint is not technical.
The first 100 signups through this link get $30 in free credits to test with. Build the same receptionist and check the numbers yourself.
Start on Retell →Building AI at your company? Eight Labs consults for enterprise, SMEs and startups. Details at theaihow.com.
For most businesses, Retell is the best overall AI voice agent platform in 2026 — not because it is the fastest, but for the combination of strong latency, the highest reliability of the six we tested (96.6%), predictable published pricing, and HIPAA included. Vapi is the pick for fastest setup and outbound, ElevenLabs for the fastest response time, and LiveKit for engineering teams that want total control.
Vapi is faster to set up (its Composer builds the whole agent from one sentence) and better for high-volume outbound. Retell is better for reliability, transparent pricing and regulated use cases because HIPAA is included. Pick Vapi if you never want to touch config; pick Retell if you want to see your real per-minute bill.
ElevenLabs. Because it owns its own speech-to-text and text-to-speech stack rather than stitching third parties together, it posts the lowest median response time. In a controlled cross-check it took the median at 1.73 seconds.
About 10.5 cents per minute all-in for a real inbound call — roughly half a cent for speech-to-text, 4.5 cents for the language model, 2 cents for text-to-speech, under a cent for telephony, and a 5 cent platform fee. Vendors quoting 5 cents are quoting only the platform fee. Published ranges run from 7 to 31 cents depending on the model and voice you pick.
Retell advertises HIPAA support included. Vapi lists HIPAA at about $2,000/month plus $1,000 for zero data retention — roughly a $24,000/year gap for the same box ticked. Treat any compliance claim as a checkbox, not a contract, and confirm the paperwork and data-retention settings with the vendor before you build.
Synthflow and Voiceflow. Synthflow's voice tier is now enterprise-only from about $30,000/year, and Voiceflow's voice tier requires a sales call before you can try it. If a platform will not let a builder swipe a card and start, that tells you who it is built for.
Watch the full 16-minute test, with every number on screen and the live calls, on YouTube.
Watch on The AI How →