Retell AI review

Retell AI is a platform for building, testing and running AI voice agents that answer and place phone calls, with chat agents for the web and SMS built the same way ^2,7. You write a single prompt or a conversation flow, attach tools and a knowledge base, and connect a Retell number or your own SIP trunk ^2,19.

Retell charges by the minute with no platform fee ¹. In G2's own hands-on customer-service test it ranked second of nine agents ²⁴. TechCrunch covered it in 2024 as a Y Combinator-backed platform for voice agents that answer customer calls ²⁷.

Each agent runs on a language model you choose, with GPT 5.6 Terra as the default ¹⁸, plus a voice and speech recognition in one of 55 languages ⁶. During a call it can call your APIs through custom functions, run code, use MCP servers, book through Cal.com or Calendly, update Salesforce or HubSpot, send an SMS and transfer the call ^3,20. Transfers can be cold, warm with a private whisper to the person taking over, or run by a second AI agent that briefs the destination before bridging the caller ⁴.

Before launch you can chat with the agent in a playground, run graded simulation tests in batches, and place web or phone test calls ⁸. Versions are drafted, published and pointed at prod or staging tags, so a phone number can switch versions without being rewired ⁹. Outbound campaigns run as batch calls from a CSV list ⁵. After each call, Retell keeps the transcript and recording and extracts a summary, sentiment, a success flag and your own custom fields ^12,13.

Retell lists $0.07 to $0.31 a minute for voice agents, with $10 in free credits and no minimums ¹. A minute is the sum of its parts: $0.055 for the voice engine, $0.064 for the default GPT 5.6 Terra model, $0.015 for a Retell platform voice and $0.015 for telephony on a Retell number ^1,18. That puts 1,000 minutes at about $151, including one $2 number. ElevenLabs voices cost $0.04 to $0.10 a minute instead, and add-ons such as PII removal (+$0.01), guardrails (+$0.005) or a knowledge base (+$0.005) raise the rate ¹. Twenty concurrent calls are included; each extra one costs $8 a month ¹. After a transfer the AI charge stops and only telephony keeps running ¹.

Retell is SOC 2 Type I and Type II certified and says it is HIPAA and GDPR compliant ¹⁵. Customers can self-sign a BAA and a DPA with EU standard contractual clauses at no extra fee ¹⁵. Per-agent settings choose whether to store everything, everything except PII, or only basic attributes, and retention can be set from 1 day to 2 years ^11,15,16. Retell does not operate services in the EU, and data is stored mainly in the United States ^15,17. Its privacy policy lists training the AI models behind its services as a use of personal information and does not say whether call data is excluded ¹⁷. Role-based access and custom SSO are Enterprise features ¹.

G2's own hands-on customer-service test ranks Retell second of nine agents, with 40 of 46 tasks passed, 86% accuracy and 90% policy compliance ²⁴, and G2's AI agent pages give it an overall evaluation score of 87 ²⁵. It rates 4.8 from 2,638 G2 reviews ²⁵ and 4.9 from 810 Trustpilot reviews, where the few complaints concern failed outbound calls and slow support ²⁶. Named customers with published stories include Anker, Everise and Matic Insurance ^21,22,23. VentureBeat singles out its automatic PII redaction and HIPAA support as reasons it suits regulated industries ²⁸.