Vapi (@Vapi_AI) is the platform for building and deploying voice AI agents. It now serves about a billion calls a year for companies including Amazon, Uber, and Intuit, helping businesses automate phone calls with AI. Voice is becoming the default interface between businesses and their customers, but getting agents reliable enough for production is still much harder than it looks. In this episode of Founder Firesides, co-founders @jordan_dearsley and @nikhilro_ sit down with @gustaf to share the long path to product-market fit, from pivoting more than a dozen times to building an AI therapist that eventually became the foundation for Vapi. They explain why voice was the first idea that felt inevitable, and how sticking with that conviction before the technology was ready eventually paid off. 00:05 — Powering a billion calls a year 02:12 — Why voice AI suddenly started working 04:57 — More than a dozen pivots 09:08 — From calendar app to AI note taker 13:23 — Starting over in San Francisco 14:14 — The AI therapist that became Vapi 17:56 — Finding PMF 22:47 — Why the model labs won’t replace Vapi 26:49 — The future of voice AI