OpenAI split a voice model’s brain. Then one team deleted 23,000 lines of code.

Building an AI voice agent has always been clunkier than it seems. Most voice agents are really a chain of systems passing a conversation back and forth. What you say gets turned into text so a model can figure out how to respond, then that answer has to be turned back into speech; it’s easy to see why things can get robotic fast.

Native Voice Architecture

Now, OpenAI is trying to collapse that stack. On Wednesday, the company launched GPT-Live-1 in its API, bringing the native, full-duplex voice architecture behind ChatGPT voice mode to outside developers for the first time. Instead of making developers manage the entire chain, it wants one model to handle the conversation while the heavier thinking happens elsewhere. Full-duplex voice delegation GPT-Live-1 operates as the conversational frontline. Because it’s natively full-duplex, it can keep up with a conversation as it happens, including when someone cuts in mid-sentence, without developers coordinating separate systems.

How It Works

The voice model doesn’t have to do all the work alone. When a request needs more time or more processing, GPT-Live-1 can hand it off to another model in the background. That could be GPT-6 Astra, a smaller model like Luna, or something from another provider entirely. Waiting on a bigger model can make a voice agent painfully awkward. Ask a difficult question, and you can end up sitting in silence while the model works through it. GPT-Live-1 can keep the conversation going instead - filling pauses, acknowledging the speaker - then work the answer in once the backend is finished.

Performance

OpenAI says GPT-Live-1 performs 30 percentage points better than GPT-Realtime-2.1 on Full Duplex Bench. Paired with GPT-6 Astra at medium reasoning, it also takes the top spot on the 𝜏³-benchmark.

Delegation Interface

OpenAI exposes delegation through an event-driven interface. The voice session generates a delegation_id, sends context to whatever backend system is handling the heavier work, and gets the result back through an event called session.commentary.append. The voice model folds that result into the ongoing conversation rather than reading a block of text aloud. Developers can still see what the model hears and says and control when it takes a turn - they just don’t have to build the entire conversation out of separate systems.

Early Results

Early customers have already seen significant benefits from using GPT-Live-1. Tony Stoyanov, co-founder and CTO of EliseAI, a healthcare company testing the API, said the move shrank his codebase by 80%. His team could spend that time on the patient experience instead - making it easier to book appointments and navigate care. The language-learning company Speak saw the difference in the conversations themselves. In early tests of its Live Tutor Lessons, GPT-Live-1 was nearly 80% less likely to interrupt someone who had simply paused to think.

Pricing

GPT-Live-1 costs $0.05 per minute, or about $3 an hour. Then there’s whatever developers choose to run behind it. If GPT-Live-1 hands a request to GPT-6 Astra, the developer pays for that call too. The more often an agent reaches for a reasoning model, the faster the bill climbs. OpenAI has been cutting API prices as competition from Anthropic, Google, and Chinese labs heats up, but frontier reasoning still isn’t free.

Platform Control Tradeoffs

With the older cascaded approach, teams can choose a different provider for each part of the voice stack and swap pieces out when they want. GPT-Live-1 takes over more of the conversation, which also means handing more of it to OpenAI. The bet is that developers will give up some of that control if it means voice agents can finally keep up with the people talking to them.