Retell uses OpenAI GPT-6 Astra and Codex to power 100M monthly calls

KEY POINTS

1. Retell reported it uses OpenAI models — GPT-6 Astra, which topped Retell’s internal voice-agent benchmark, and Codex — to power roughly 100 million monthly voice calls.
2. The company also says this approach contributes to a $1.6M annual revenue run rate per employee.
3. It illustrates how state-of-the-art OpenAI models are being deployed to scale commercial voice-agent products and drive unusually high revenue efficiency at a startup.