Configure a Retell AI inbound voice agent with a custom LLM and retrieve post-call transcripts via the REST API

Steps

1. POST to /create-agent with voice_id, llm_websocket_url (your custom LLM endpoint), begin_message, and general_prompt to define the agent configuration
2. Import or provision a phone number via POST /import-phone-number (for BYO carrier) or purchase via the dashboard, then link it to the agent by specifying the agent_id
3. Expose a WebSocket server at the llm_websocket_url that accepts the Retell LLM protocol — receive interaction_type: response_required messages and return response_type: response with content
4. After a call ends, retrieve the call record via GET /get-call/{callId} to access the transcript array, call_analysis object, and recording_url
5. Use POST /list-calls with optional filtering by agent_id or date range for batch transcript retrieval
6. Configure webhook events (call_started, call_ended, call_analyzed) via the dashboard or POST /create-agent with a webhook_url to receive real-time notifications