Retell AI

Retell AI is a real-time conversational voice platform that lets businesses build, test, deploy, and monitor production-ready AI voice agents for phone-based customer interactions. Rather than relying on rigid, menu-driven IVR systems, Retell combines low-latency speech recognition, large language models, and realistic text-to-speech to create agents that hold natural, human-like conversations, understand context, and take real actions like booking appointments, checking order status, or transferring to a live representative.

At the core of the platform is a highly configurable, drag-and-drop conversation flow builder with built-in guardrails, real-time function calling, and streaming retrieval-augmented generation that keeps agents grounded in a business's latest knowledge base. Teams can choose from a range of LLMs including GPT, Claude, and Gemini models, pair them with voice providers like ElevenLabs or Retell's proprietary voices, and connect to any existing telephony setup via SIP trunking or native Twilio and Vonage integrations. Built-in simulation testing, post-call transcripts, and a quality assurance layer let teams validate and continuously refine agent behavior before and after launch.

Retell AI serves industries with high call volumes and strict reliability needs, including healthcare, financial services, insurance, logistics, retail, and debt collection, with customers like Pine Park Health, SWTCH, and Medical Data Systems using it to boost scheduling satisfaction, cut support costs, and scale collections. The platform is SOC 2 Type II certified, HIPAA-ready, and GDPR compliant, with an Enterprise plan adding dedicated servers, custom SSO, role-based access control, and white-glove implementation support for organizations running voice AI at production scale. Founded in 2023 by a team out of Y Combinator's Winter 2024 batch, Retell AI has grown quickly to serve thousands of businesses handling real customer calls.

Retell AI's Pay-as-you-go plan starts at $0 with $10 in free credits, no commitments, and full platform access. AI Voice Agents cost $0.07-$0.31 per minute depending on the LLM and voice provider selected, with a base cost breakdown of $0.055/min for Retell's voice infrastructure, $0.015-$0.040/min for text-to-speech (ElevenLabs is priciest at $0.040/min), and LLM costs ranging from $0.003/min (GPT 5 nano) to $0.16/min (GPT 5.5). AI Chat Agents start at $0.002+ per message. The plan includes 20 free concurrent calls, with additional concurrency at $8/month each; the first 10 knowledge bases are free, then $8/month each; phone numbers cost $2/month and verified numbers have a one-time $10 fee. Add-ons include Knowledge Base (+$0.005/min), Batch Call (+$0.005/dial), Branded Call ID (+$0.10/outbound call), Advanced Denoising and Safety Guardrails (+$0.005/min each), PII Removal (+$0.01/min), and AI Quality Assurance ($0.10/min after 100 free minutes). The Enterprise plan offers custom pricing with dedicated stable servers, custom SSO, role-based access control, custom MSA/DPA/BAA terms, high concurrent call caps, and 24/7 support with a dedicated portal.