Retell AI

Retell AI is a platform for building and deploying conversational voice agents for phone-based customer interactions, inbound support lines, outbound sales calls, appointment reminders, and intake flows that operate at scale without human agents handling each call. It manages the full voice AI stack: speech-to-text, LLM-based response generation, text-to-speech, interruption handling, turn management, and call lifecycle, all optimized for the sub-500ms latency that makes voice conversations feel natural rather than robotic. The workflow builder creates branching conversation logic for complex call flows without code: define the path for different caller responses, set conditions for escalation to a human agent, and configure confirmation steps for appointment or transaction workflows.

What differentiates Retell from raw voice APIs is the built-in operational layer: phone number provisioning across 50+ countries, call recording with transcript generation, call analytics dashboards, webhook integrations for real-time event processing, and native CRM integrations with HubSpot and Salesforce for automatic call logging. Used by healthcare practices automating appointment scheduling and reminder calls, real estate agencies handling property inquiry routing, insurance companies managing claims intake, and SaaS companies building AI customer service phone channels. Developer-friendly: the API is well-documented with SDKs in Python and JavaScript, a testing environment for call simulation before production, and usage-based pricing that starts at $0.05–$0.07 per minute depending on configuration.