Retell builds voice AI agents that automate phone operations, and its stack reads like a telephony company fused with an LLM shop: SIP and media servers (Asterisk, FreeSWITCH, Kamailio), carrier APIs (Twilio, Telnyx, Plivo), and contact-center integrations (Five9, Genesys, Amazon Connect, Avaya) alongside OpenAI, Gemini and PyTorch. Senior-heavy, engineering-dominant hiring targets scaling call reliability and enterprise deployment.
Retell, founded in 2023 and headquartered in Redwood City, California, offers a platform for creating, testing, launching and monitoring AI-powered voice agents. Its customers come from healthcare, insurance, financial services and logistics, where the agents handle and automate call workflows. The privately held company has 51–200 employees and hires across the United States, Romania, the Philippines, Singapore and China. Its product connects to carrier networks and enterprise contact-center platforms, and the team also supports customer deployments and a channel partner program.
Retell uses Python, TypeScript, React and Node.js, telephony tools like Asterisk, FreeSWITCH, Kamailio, Twilio, Telnyx and Plivo, plus OpenAI, Gemini and PyTorch for AI.
Its stack includes Five9, Genesys, Amazon Connect and Avaya, and job posts reference telephony integrations and integration with customers' existing systems.
Retell hires in the United States, Romania, the Philippines, Singapore and China, with engineering the dominant function and most roles at senior level.
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Retell's technology stack, projects, and hiring signals are inferred from public hiring and company data — career pages, public listings, and company web presence — then clustered and de-duplicated. Figures are estimates that refresh over time. Read our full methodology →
This is not an official vendor or customer list. It is a technology-adoption signal inferred from public data, intended for B2B research.
