Retell AI runs 100M monthly calls on OpenAI models
OpenAI reports that voice-AI platform Retell AI now serves more than 4,000 businesses, with monthly call volume growing from 30 million in early 2026 to over 100 million by September, and OpenAI models generating responses for 80% of those calls. Retell says customer resolution rates exceed 80%, citing Anker's reported 80.4% case resolution rate and a Net Promoter Score of 63, while Pine Park Health's scheduling agent reached a 55.7% booking rate. In its vCX benchmark dated October 13, 2026, GPT-6 Astra ranked first for instruction following at 89.7%, and Retell engineers use Codex for code research, feature building and debugging plus GPT-6 Astra's computer use to test front-end interfaces.
The report documents a large-scale production deployment of OpenAI models in contact-center voice agents, including 100 million monthly calls, more than 1 trillion tokens consumed across OpenAI models, and a Codex-based engineering workflow, though all adoption and performance figures are vendor-reported.
Retell AI(opens in a new window) is a voice AI platform for contact center operations, helping businesses build agents that can answer questions, take action, and connect a caller with a person when needed. Its platform now serves more than 4,000 businesses, with monthly call volume growing from 30 million in early 2026 to more than 100 million by September.
As Retell serves more enterprises with complex workflows, it uses OpenAI models to keep call quality and reliability high. Today, OpenAI models generate responses for 80% of calls on Retell, with customers achieving resolution rates above 80%. Retell has also surpassed 1 trillion tokens consumed across OpenAI models, reflecting the scale of that adoption.
Retell’s engineers use Codex throughout development, from researching unfamiliar code to building features and debugging issues, and GPT‑6 Astra to test front-end interfaces.
“We choose models the way our customers choose vendors: on real calls, not demos. OpenAI keeps earning its spot.”
—Bing Wu, Co-founder and CEO, Retell AI
Choosing OpenAI models for the demands of a live call
Enterprise voice agents need to follow company policies and stay within their assigned roles, even as conversations change. Retell built its vCX benchmark to compare dozens of models using difficult, multi-turn conversations drawn from real production scenarios.
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