From the source
Retell AI, a voice AI platform for contact center operations, says OpenAI models now generate responses for 80% of the calls on its platform, which grew from 30 million monthly calls in early 2026 to more than 100 million by September.
- The company serves more than 4,000 businesses and has consumed over 1 trillion OpenAI tokens, with customers reporting resolution rates above 80%.
- Retell built its vCX benchmark to compare models on difficult multi-turn conversations drawn from production scenarios; in its October 13, 2026 benchmark, GPT-6 Astra ranked first for instruction following at 89.7%.
- Evaluations run before GPT-6 Astra's launch showed GPT-5.5 ranking highest among models on non-hallucination rate (88.0%) and tool-call correctness (88.3%) with reasoning enabled, ahead of Gemini-3.1-Pro and Claude-4.6.
- Retell uses dedicated servers with OpenAI and regional API endpoints to cut network travel time and meet data residency needs in healthcare and financial services.
- At Anker, agents handling Tier-1 post-sales support in the US and UK reported an 80.4% case resolution rate and an NPS of 63, while Pine Park Health recovered medical-assistant time equal to 2.1 full-time roles.
