Build more natural voice experiences with GPT‑Live‑1 in the API

Build more natural voice experiences with GPT‑Live‑1 in the API | OpenAI

September 10, 2026

Build more natural voice experiences with GPT‑Live‑1 in the API

GPT‑Live‑1 brings ChatGPT’s natural, full-duplex conversations to the API, with more control over how voice agents speak and act.

We’re launching GPT‑Live‑1 in the API, giving developers a powerful, natural voice model for building voice-enabled apps and business workflows. First introduced in ChatGPT, GPT‑Live‑1 is capable of listening and speaking at the same time, and, as seen with Codex and ChatGPT Work⁠(opens in a new window), can delegate deeper reasoning and actions to the models and tools it is paired with.

For the API release of GPT‑Live‑1, we’ve focused on new capabilities that let developers steer and customize voice experiences around their users, workflows, and goals. A core GPT‑Live‑1 strength, smooth interruption handling, is already delivering business impact: in early evaluations, Speak found that GPT‑Live‑1 gave learners more time to think before the language tutor responded, cutting interruptions by almost 80% versus previous turn-based systems.

Key strengths of GPT‑Live‑1 in the API:

• Interruption handling: Improves interruption handling via a single model that reasons over incoming and outgoing audio together, avoiding the latency and brittle handoffs of chained STT–LLM–TTS architectures.
• Reasoning & tool calling delegation: GPT‑Live‑1 can delegate reasoning and tool calls to a backend text model like GPT‑6 Astra or a third-party model.
• Tone, pace, and style: Lets developers shape an agent’s tone, pace, and conversational style through the system prompt.
• Silent context management & background noise: Better handles background noise and silence without interrupting the conversation or narrating every step out loud.
• Long-session reliability: Improves context retention and conversational quality across extended interactions.
• Telephony support: Enables deployment of full-duplex voice agents for phone calls, from restaurant reservations to customer support.

Start a session and speak naturally. Interrupt, laugh, change your mind - try it at home or in a loud space like a coffee shop or city street.

See what it can do

• Talk over it—naturally. Ask for help, then interrupt mid-response to change the question or add detail.
• Take it with you. Try a conversation while walking outside or with everyday background noise, and see how it stays with you.
• Make it playful. Laugh, hesitate, use short acknowledgments, or briefly talk to someone nearby—then continue the conversation.

Simplify your voice-agent architecture and reduce voice latency

Traditional voice agents stitch together speech-to-text, a reasoning model, and text-to-speech. Each handoff adds latency and creates more opportunities to lose timing, context, or the natural rhythm of a conversation. Developers are often the ones left coordinating those stages, including what happens when someone interrupts, pauses, or changes direction.

GPT‑Live‑1 handles listening and speaking in a single model, simplifying the voice layer. It can respond to interruptions and acknowledgements as they happen, while delegating deeper reasoning to the back end. This lets the conversation continue while work happens in the background.

> “ Compared to our cascaded build, GPT‑Live‑1 simplified our code base by 80% and removed 23K lines of code. This enabled natural, real-time patient conversations & freed our team to improve the experience from booking an appointment to navigating care.”

—Tony Stoyanov, Co-Founder & CTO

Developers choose the models, tools, and agent harness behind the conversation. For example, they might pair GPT‑Live‑1 with a model like Luna for high-volume tasks like scheduling or order updates, and use a model like Astra for complex customer issues that require reasoning. That flexibility lets developers match reasoning depth, speed, and cost to each task.

GPT‑Live‑1 natively provides ASR transcripts and response text. It also offers strong alphanumeric understanding and supports keyword biasing. Although GPT‑Live‑1 is not a turn-based model, it natively supports turn detection, so developers can continue to build around explicit turn boundaries.

Measuring the full-duplex advantage

Across our evaluations, GPT‑Live‑1 improves Full Duplex Bench performance by 30 percentage points over GPT‑Realtime‑2.1, with large gains in turn-taking latency and interactive behavior. Paired with GPT‑6 Astra at medium reasoning effort, it also ranks #1 on Tau3, which measures frontier voice-agent intelligence on end-to-end tasks.

Evaluates spoken customer-service tasks in airline, retail, and telecom domains. Pass@1 measures task success; the headline gives each domain equal weight.

• GPT Live backend: Astra (medium).

Evaluates spoken banking support with knowledge retrieval and account tools. Pass@1 is the fraction of 97 banking_knowledge tasks completed successfully.

• GPT Live backend: Astra (medium).

Evaluates pause handling, conversational turn taking, interruptions, and backchannels.

Tests reactions to background speech, speech to another person, listener backchannels, and interruptions.

Measures how quickly the agent starts its reply after the user finishes a turn.

Tests tool use from spoken requests containing natural pauses, hesitations, and self-corrections. Pass@1 scores the tool-call sequence.

• GPT Live backend: Terra (low).

Evaluates the spoken answer to tool-using requests containing pauses, hesitations, and self-corrections. Scores how well the answer matches the reference intent.

• GPT Live backend: Terra (low).

What customers are saying

> “ Adding GPT‑Live‑1 into Yelp Host and Hatch improved turn-taking and accuracy over our traditional voice architecture. When Yelp Host uses GPT‑Live‑1 to answer calls, like reservations and food orders, we're seeing meaningful improvements in call handling rates. Callers are also speaking fuller, more natural sentences, which tells us the experience on the other end of the phone feels genuinely different.”

—Alex Levy, Chief Technology Officer

> “ A good language tutor knows when to give learners space and when to step in, and GPT‑Live‑1 brings that naturalness to Speak’s Live Tutor Lessons—in our early evaluations, it cut interruptions during thinking pauses by almost 80% compared with previous turn-based systems.”

—Andrew Hsu, Co-founder & CTO

> “ GPT‑Live-1 shows what a...