Retell AI
Hosted platform for building, testing, deploying and monitoring AI phone agents, with single-prompt, multi-prompt and conversation-flow agent shapes, function calling and call/agent transfers.
Description
Retell AI is a phone-agent platform. Agents can be built as a Single-prompt agent (one open prompt), a Multi-prompt agent (state machine of prompts with transition conditions), or a Conversation Flow agent (explicit node graph with transition conditions). Function Calling, custom functions and code tools let the agent perform real-world actions; Transfer Call and Transfer Agent nodes hand off to humans or to other Retell agents. The dashboard exposes per-language selection with explicit accuracy trade-offs across the supported speech-recognition and voice providers.
Solution
Hosted phone-agent loop. The platform owns the STT, LLM orchestration, TTS and turn-taking layers; the developer authors agent behaviour as a Single-prompt, Multi-prompt (state machine of prompts with transition conditions) or Conversation Flow (node-and-transition graph) agent. Function calls and code tools execute external actions; Transfer Call hands off to humans and Transfer Agent hands off to another Retell agent.
Primary use cases
- lead qualification voice agents over telephony
- customer support and dispatch phone agents
- receptionist agents with call transfer
- multilingual phone agents with language selection
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Diagram, neighbourhood map, code examples, related patterns and full provenance.