Explainer · Full-duplex voice AI
What is full-duplex voice AI?
Why AI on the phone finally sounds like a conversation.
Full-duplex voice AI hears and speaks at the same time, the way two people on a phone call do. Older voice AI took turns like a walkie-talkie, with a separate switch listening to the line to decide whose turn it was. That's why it cut people off mid-sentence, or talked straight over them.
- You say “mm-hm”. It hears a sound and stops mid-sentence.
- A beat of silence while it works out whose turn it is.
- You say “…hello?”
- It picks up again, from somewhere in the middle.
- You say “mm-hm”. It keeps talking.
- You say “wait”. It stops and listens.
Voice AI used to take turns.
Like a walkie-talkie.
Until recently, most voice AI on the phone worked in turns. The AI talked, then stopped and listened, and a separate switch listening to the line decided whose turn it was: when you had finished, and whether you were cutting in. The switch had only the sound to go on.
That one design is behind a lot of what people dislike about talking to a bot:
- You said “mm-hm” to show you were listening, and it stopped mid-sentence.
- Switch interruptions off to stop that, and it talked straight over you when you said “wait”.
We ran into both ourselves. Before we moved to full duplex, our own AI kept stopping mid-sentence on our test calls, and when we switched interruptions off to fix it, it talked straight over us.
Full duplex: it listens while it talks.
Like a phone call.
“Full duplex” is an old telephone term: both people can talk and be heard at the same time. A full-duplex voice model works the same way. It listens and talks at once, and it decides for itself, from what you say, when to stop and when to keep going. There's no separate switch cutting it off the moment it hears a sound.
Full-duplex voice AI isn't a new idea. What changed is that OpenAI built one good enough for real business calls: GPT-Live, which it launched in ChatGPT in July 2026 and opened to developers like us on September 10 as GPT-Live-1. Every demo on this site, and our own AI, runs on it.
What you'll notice.
Mostly, what you won't.
- You can cut in mid-sentence, and it stops to listen.
- It's built to hear an “mm-hm” as you listening, and keep going. A “wait” stops it.
- No switch is timing the gaps in the sound to decide it's its turn.
- Change your mind halfway through a sentence, and it keeps up.
It's still an AI.
It just doesn't talk like a robot.
It never pretends to be a person: ask, and it tells you it's an AI. It answers from what it has been told about the business, takes a message when it doesn't know, and can hand the call to a person. Full duplex changes how the conversation feels, not what the AI is.
What an AI receptionist does for a business ↗
Try to break it.
Do what the old bots couldn't handle.
This is the front desk we built for a made-up Miami plumbing company. Every technician is out on a job, so the AI is answering. Press the button and be the customer:
- Cut in halfway through one of its sentences.
- Say “mm-hm” while it's talking. Then say “wait”.
- Ask for someone to come out, then change your mind about the day.
- Ask it something nobody would have scripted.
About four minutes, in your browser. No sign-up.
Questions people ask
What does full duplex mean?
It's a telephone word: both people can talk and be heard at the same time, as on an ordinary phone call. Half duplex is one side at a time, like a walkie-talkie, where you say "over" to hand back.
What's the difference between half-duplex and full-duplex voice AI?
Half-duplex voice AI takes turns: a separate switch listens to the line and decides when you've finished and when you're cutting in, and the AI stops or starts on its say. Full-duplex voice AI listens and talks at the same time, and the model itself decides, from what you say, when to stop and when to keep going.
Why did AI phone calls cut people off?
Because the switch deciding whose turn it was had only the sound on the line to go on. An "mm-hm", a cough or the AI's own voice coming back through a speakerphone could sound like the caller starting to talk, so the AI stopped mid-sentence.
Will callers know it's an AI?
It never pretends to be a person: ask, and it says it's an AI. What has changed is how the conversation feels. Callers can interrupt it and change their mind halfway through a sentence, the way they would with a person.
Which full-duplex model do your agents run on?
GPT-Live-1, made by OpenAI. OpenAI launched GPT-Live in ChatGPT in July 2026 and opened it to developers as GPT-Live-1 on September 10, 2026.
Do Talk Society's AI employees use full-duplex voice AI?
Yes. Every demo on this site and our own AI run on GPT-Live-1, and it's what we build AI employees on by default, for the phone and for your website.
Does it cost more?
It's priced like everything we build: after a build from $1,000, 30 cents a minute of talk time, the voice AI and the phone line included, with no monthly fee.
How can I test it?
Open the demo on this page and try to throw it: interrupt it, say "mm-hm" while it talks, then say "wait", or change your mind halfway through a booking. When we build yours, you test it the same way before it goes live, and tell us what to change.
Hear the difference.
Then book your demo.
The quickest way to understand full duplex is to talk to it. If you like what you hear, book a demo: our AI asks a few questions about your business and books you a call with our team.
P.S. Interrupt it. Talk over it. Change your mind halfway through. If it keeps up with you, picture it answering your phone.