Introducing gpt-realtime and Realtime API updates

Today we’re making the Realtime API generally available with new features that enable developers and enterprises to build reliable, production-ready voice agents. The API now supports remote MCP servers, image inputs, and phone calling through Session Initiation Protocol (SIP), making voice agents more capable through access to additional tools and context.

We’re also releasing our most advanced speech-to-speech model yet—gpt-realtime. The new model shows improvements in following complex instructions, calling tools with precision, and producing speech that sounds more natural and expressive. It’s better at interpreting system messages and developer prompts—whether that’s reading disclaimer scripts word-for-word on a support call, repeating back alphanumerics, or switching seamlessly between languages mid-sentence. We’re also releasing two new voices, Cedar and Marin, which are available exclusively in the Realtime API starting today.

Since we first introduced the Realtime API in public beta last October, thousands of developers have built with the API and helped shape the improvements we’re releasing today—optimized for reliability, low latency, and high quality to successfully deploy voice agents in production. Unlike traditional pipelines that chain together multiple models across speech-to-text and text-to-speech, the Realtime API processes and generates audio directly through a single model and API. This reduces latency, preserves nuance in speech, and produces more natural, expressive responses.

Introducing gpt-realtime

The new speech-to-speech model—gpt-realtime—is our most advanced, production-ready voice model. We trained the model in close collaboration with customers to excel at real-world tasks like customer support, personal assistance, and education—aligning the model to how developers build and deploy voice agents. The model shows improvements across audio quality, intelligence, instruction following, and function calling.

Audio quality

Voice sample - Marin