Retell Ai

Retell AI focuses on the low-latency end of voice agent infrastructure — sub-500ms response times are a key differentiator for conversational AI use cases where perceptible pauses break the interaction. The API covers agent creation, inbound/outbound call management, phone number provisioning, and campaign-style outbound dialers. Good fit for teams building AI sales callers, customer service agents, and interactive voice response systems. Confidence is docs-derived.

REST API at api.retellai.com. Resources: agents, calls, phone-numbers, batches. POST /v2/create-agent creates a voice agent (llm_websocket_url, voice_id, agent_name, prompt). POST /v2/create-phone-call initiates an outbound call ({from_number, to_number, agent_id}). GET /v2/get-call/{call_id} retrieves call details including transcript. POST /v2/create-batch-call submits an outbound dialer batch. Webhook: configure webhook_url on agent to receive per-event callbacks.

API key auth: Authorization header. Keys from Retell AI Dashboard. HTTPS enforced. Bring your own phone numbers (Twilio/Vonage) or purchase via Retell AI. Webhook events signed for verification. No OAuth2.

Call status lifecycle: registered → ongoing → ended. Ended calls include transcript, recording, call analysis (sentiment, intent). Batch campaigns track completion per-call. Rate limits: concurrent call limits per plan. Retell AI uptime at status.retellai.com. LLM latency is the primary variable for call quality — Retell routes through optimized inference paths.

docs.retellai.com covers agent creation, call management, phone setup, and webhook integration with clear examples. Getting started: create account, set up agent, first call in under 10 minutes. Active developer community. Free trial available.