Retell AI

What is Retell AI?

Retell AI is a platform for building, testing, deploying, and monitoring AI-powered voice agents that handle phone calls with human-like conversations. It uses large language models to power inbound and outbound call automation, replacing rigid script-based systems with agents that can reason and respond naturally. The platform targets businesses that handle high volumes of phone interactions, from healthcare providers and insurance companies to sales teams and customer support operations. Unlike traditional IVR systems, Retell AI agents can book appointments, process payments, transfer calls with context, and update records in real time.

Key Features

• Low-Latency Orchestration: Achieves approximately 600ms response time using proprietary turn-taking models, keeping conversations fluid and natural rather than stilted.
• No-Code Agent Builder: A visual builder lets non-engineers create and modify agents quickly, with support for single and multi-prompt conversation flows and prompt-based configuration.
• Multilingual Support: Handles 31+ languages and can dial phone numbers in any country, with verified numbers available to reduce spam flagging.
• Knowledge Base with Auto-Sync: Pulls accurate answers from a connected knowledge base that syncs automatically from webpages (via sitemap), uploaded files such as PDFs and spreadsheets, or manual input.
• Call Transfer and Handoff: Supports warm and cold transfers with context summaries passed to human agents, plus fallback mechanisms for edge cases.
• Omnichannel Messaging: Integrates SMS and chatbot flows alongside voice so agents to send personalized texts with variables, escalation links, or promo codes within the same workflow.
• Post-Call Analysis: Provides custom insights and performance monitoring after each call, with simulation testing available via manual or AI-simulated calls.
• Batch Calling: Scales outbound campaigns to millions of calls with 99.99% uptime and concurrent call support.

Use Cases

• Sales and Marketing Teams: Use Retell AI for outbound outreach, lead qualification, and appointment setting, reducing the manual workload on sales reps and increasing contact rates at scale.
• Healthcare Providers: Automate appointment confirmations, prescription refill requests, and scheduling follow-ups. One reported outcome is a 38% increase in scheduling NPS after deploying AI-driven call handling.
• Customer Support Operations: Handle inbound queries around billing, order status, and routine troubleshooting without requiring a live agent, with smooth escalation to humans when needed.
• Education Providers: Automate admissions inquiries and enrollment calls during high-volume periods. TripleTen, a bootcamp provider, uses Retell AI to manage inquiry surges for enrollments.
• Insurance and Financial Services: File claims, check loan or transaction status, and guide callers through paperwork over the phone without live agent involvement.

Strengths and Weaknesses

Strengths:

• Ease of use and intuitive setup, rated 4.8/5 on G2 across 1,656 verified reviews, with ease of use mentioned in 495 of those reviews.
• Low latency and realistic voice quality, with benchmarked response times around 780ms and natural turn-taking that users consistently highlight.
• Flexibility for developers and non-developers alike, including LLM swapping, API access, CRM integrations, and solid documentation.
• Fast time to production, with deployments reportedly achievable in as little as 5 minutes using the no-code builder.

Weaknesses:

• The dashboard can feel overwhelming for new users, particularly those without prior experience building voice or telephony workflows.
• Occasional voice inconsistencies in tone and inflection have been noted in user reviews.
• Some users report call transfer failures, including 403 SIP errors and warm transfer caller ID issues showing the agent's number rather than the user's number.
• High end-to-end latency in specific configurations, with some users reporting P90 latency exceeding 3 seconds in Rigid Mode versus around 1,300ms in Flex Mode.

Pricing

Retell AI uses a pay-as-you-go model with no fixed monthly subscription for most users. Costs vary depending on which voice engine, LLM, and add-ons are selected per call.

• Free Tier: $0 to start, includes $10 in free credits, 20 free concurrent calls, and 10 free knowledge bases.
• Conversation Voice Engine: $0.055/minute for Retell Voice Infrastructure.
• Text-to-Speech: Starting at $0.015/minute for Retell Platform, Minimax, Fish, Cartesia, and OpenAI voices; $0.040/minute for ElevenLabs voices.
• Speech-to-Speech LLM: $0.07/minute for GPT Realtime mini; $0.345/minute for GPT Realtime 1.5 or GPT Realtime Standard/Fast.
• Add-ons: Knowledge Base and Advanced Denoising each add $0.005/minute; PII Removal adds $0.01/minute; Branded Call adds $0.10 per outbound call; Batch Call adds $0.005 per dial.
• Telephony: $0.01/minute via Retell Twilio; optional phone numbers at $2.00/month each.
• AI Chat Agent: $0.002/message.
• Enterprise: Custom pricing available via sales, with volume discounts potentially bringing base rates to $0.05/minute or lower.

Total per-minute costs for a full setup typically range from $0.07 to $0.31 depending on selected components. As a rough example, 1,000 minutes using ElevenLabs voice, Claude 3.5 as the LLM, and Twilio telephony works out to approximately $140.

FAQ

Is Retell AI free or paid?

Retell AI is a paid platform. Pricing details are not specified in available documentation, but it is designed for businesses handling high volumes of phone interactions.

How does Retell AI work?

Retell AI uses large language models to power voice agents that handle inbound and outbound phone calls. It replaces rigid script-based IVR systems with agents that can reason, respond naturally, and perform tasks like booking appointments, processing payments, and updating records in real time.

Is Retell AI legit?

Retell AI is a real platform used by businesses in healthcare, insurance, education, and customer support. Documented users include TripleTen, a bootcamp provider, which uses it to manage enrollment inquiry surges.

Is AI calling illegal?

Retell AI provides verified phone numbers to reduce spam flagging, but the legality of AI-powered calls depends on applicable laws in your jurisdiction. Retell AI itself does not address the legal compliance obligations of its users within available documentation.

Who are the competitors of Retell AI?

Retell AI's direct competitors are not listed in available documentation. It operates in the AI voice agent space alongside other platforms that automate phone-based business communication.

Can Retell AI handle calls in multiple languages?

Yes. Retell AI supports 31 or more languages and can dial phone numbers in any country.

Does Retell AI require coding to set up?

No. Retell AI includes a no-code visual builder that allows non-engineers to create and modify agents without writing code.

How fast does Retell AI respond during calls?

Retell AI achieves approximately 600ms response time using a proprietary turn-taking model, which is designed to keep conversations fluid rather than stilted.

Can Retell AI transfer calls to a human agent?

Yes. It supports both warm and cold call transfers and passes context summaries to human agents during handoffs, with fallback mechanisms available for edge cases.

Does Retell AI support outbound calling campaigns?

Yes. Retell AI supports batch calling for outbound campaigns, with concurrent call support and a reported uptime of 99.99%.

What industries use Retell AI?

Documented use cases include healthcare, insurance, financial services, customer support, sales and marketing, and education.

Can Retell AI send text messages?

Yes. Retell AI includes omnichannel messaging that allows agents to send SMS within the same workflow, including personalized texts with variables, escalation links, or promo codes.

Is it legal to publish a novel written by AI?

This question falls outside the scope of Retell AI, which is a voice agent platform and does not involve written content generation or publishing.