Retell

What Retell does

Retell is the #1 voice AI agent platform that enables businesses to build, test, deploy, and monitor voice AI agents for automating phone call operations. The platform offers LLM-based, human-like, voice-first conversational AI, distinguishing itself from traditional IVR and IVA voice agents with natural conversations, fast setup, and the ability to handle complex, multi-turn interactions and edge cases. Retell's proprietary Voice AI Orchestration delivers human-quality, low-latency phone conversations at scale, featuring ultra-realistic voices and a proprietary turn-taking model. The platform is highly configurable with a drag-and-drop agentic framework, real-time function calling, and streaming RAG for knowledge base integration. It includes comprehensive agent testing with built-in simulation, continuous QA, and performance analytics dashboards. Retell supports both inbound and outbound calls, integrates with various telephony providers, and offers robust testing and monitoring capabilities. It is designed to scale from quick-start simplicity to enterprise-grade security, compliance, and support, with a pay-as-you-go pricing model.

Products

• AI Voice AgentsLLM-based, human-like, voice-first conversational AI agents for automating phone calls, capable of handling complex, multi-turn, and outbound use cases.
• AI Chat AgentsAI-powered conversational agents for web and in-app chat.
• AI ReceptionistAn AI agent that answers business calls 24/7, greets callers, answers questions, books appointments, and routes calls with context.
• AI Dispatch ServiceAn AI service that answers inbound calls, captures requests, routes them to the right team, and provides customer updates for dispatch operations.
• AI Auto DialerAn AI-powered auto dialer that places calls, navigates phone trees, qualifies prospects, and books meetings or transfers hot leads to live reps.
• AI Answering ServiceIntelligent, 24/7 call handling that integrates with business workflows, routes calls, handles IVR navigation, and manages scheduling and notifications.
• AI Appointment SetterAI voice agents that book appointments by checking availability, confirming time slots, and integrating with calendars.
• AI Debt CollectionAI agents for automating payment reminders and follow-ups in debt collection.
• AI Customer ServiceAI agents designed to automate and enhance customer service operations.
• AI IVRAI-powered solution that outperforms traditional IVR systems for call routing and interaction.
• AI TelemarketingAI engine for running telemarketing campaigns, including renewals and win-back efforts.
• Knowledge BaseA feature that turns existing content (webpages, documents, custom text) into live context for AI agents to answer questions accurately and reduce hallucinations.
• Call TransferFeature enabling seamless AI-powered warm and cold call transfers to live agents or other departments, maintaining context.

Key capabilities

• LLM based, humanlike, voice-first conversational AI platform
• Proprietary Voice AI Orchestration
• Lowest Latency (~600ms)
• Ultra Realistic Voice (built from real performance data, human-guided training)
• Proprietary turn-taking model
• Highly Configurable Agentic Framework (drag-and-drop, built-in guardrails, full control)
• Real-Time Function Calling with Preset Functions (book appointments, process payments, update records, transfer calls)
• Streaming RAG for knowledge and auto Sync capability
• Comprehensive Agent Testing with Built in Simulation Testing
• Continuous QA to Ensure Performance Across Edge Cases
• Performance Analytics Dashboard
• Voice Call support
• Chat support
• Full Platform Access
• Pre-built Agent Templates
• Call Analytics and Transcripts
• Webhooks and API Access
• Concurrent Calls (20 free, higher caps for Enterprise)
• Community and Email Support
• Dedicated Implementation Support (add-on for Enterprise)
• Custom MSA/DPA terms (Enterprise)
• Role-based Access Control (Enterprise)
• Dedicated Stable Server (Enterprise)
• Custom SSO (Enterprise)
• 24/7 Omnichannel Support with Dedicated Portal (Enterprise)
• Built-in Fallback System (Enterprise)
• Built-in Safety Guardrails
• Personal Info Redaction (PII)
• Opt-out Recording & Transcription
• Custom Data Retention
• HIPAA / BAA compliance
• Custom Telephony Integration via SIP
• Webhook for real-time events
• Call Analysis
• Dynamic Routing to different Departments
• Smart Routing to Assigned Contacts
• Warm Transfer to a Human Agent with Context
• AI Agent Navigates IVR To Retrieve Information
• Intelligent Notifications & Reminders
• Pre-Screening & Caller Insights
• Customer Feedback & Surveys
• Real-Time Transcription & Summarization
• Seamless CRM & Tool Integrations
• Custom Voice Personas
• 24/7 Call Handling
• Natural, Human-Like Conversations
• Flexible Flows & Smart Routing
• Automated Follow-Ups (voicemail, SMS)
• Batch Outbound Calls
• Lead Qualification
• Objection Handling
• Integration with GPS and routing systems (for dispatch)
• PII Redaction from transcripts
• Signed and secure recording URLs

Use cases

• Automating phone call centers
• Streamlining operations
• Enhancing customer service
• Scaling call operations effortlessly
• Call routing through pre-defined, touch-tone menu options (as an alternative to IVR)
• Automating and enhancing call operations in healthcare, insurance, financial services, and logistics
• Increasing scheduling NPS and filling underutilized provider capacity (Pine Park Health)
• Handling urgent EV support at scale and cutting support costs (SWTCH)
• Handling 100% of inbound calls with a low transfer rate and collecting monthly revenue (Medical Data Systems)
• Answering every call 24/7
• Greeting callers in business name
• Answering questions (hours, location, pricing, services)
• Booking appointments straight into calendars (Cal.com, Google Calendar)
• Rescheduling and confirming appointments
• Sending confirmations and reminders for appointments
• Capturing and qualifying leads
• Routing hot leads to the right person with warm call transfer
• Following up and reminding by phone (batch call campaigns)
• Covering overflow and after-hours calls (AI answering service)
• Serving callers in multiple languages with automatic language detection
• Automating patient service, reminders, and front-desk tasks (Healthcare)
• Handling account inquiries, transfers, and support (Financial Services)
• Streamlining claims, quotes, and policy updates via voice (Insurance)
• Confirming deliveries, rerouting shipments, and notifying customers (Logistics)
• Answering bookings, routing calls, and managing appointments 24/7 (Home Services)
• Automating payment reminders and follow-ups (Debt Collection)
• Supporting orders, returns, and FAQs (Retail & Consumer)
• Managing reservations, cancellations, and guest requests (Travel & Hospitality)
• Automating patient scheduling, management, and provider coordination (Healthcare EHR integration)
• Triggering AI-powered calls from workflows and pushing results into tools (viaSocket)
• Automating workflows and triggering actions based on voice commands (Make)
• Managing phone calls, sending SMS notifications, handling customer interactions (Twilio)
• Optimizing business operations and enhancing customer interactions (InovaSolutions)
• Lead qualification, reactivation & follow-up (Omnia)
• AI Dialer Implementation (Sympana LLC)
• Streamlining lead qualification, appointment setting, and customer support (Zehaan)
• Training, research, and development of call agents with AI (Son-ia)
• Expanding business without complexity, lead management, customer experience (CRAFT Digital)
• Reducing missed opportunities, improving responsiveness, growing capacity (Coreventia)
• Streamlining business operations and enhancing customer interactions with realistic voice avatars (Aitoflo)
• Automating lead qualification, engaging prospects, routing hot leads
• Qualifying inbound leads on every call
• Syncing qualified leads to CRM
• Qualifying across phone, text, and email
• Capturing leads after-hours and on overflow
• Loan Prequalification & Application Handling
• Customer Support for Loan Servicing
• Sales & Lead Nurturing for financial services
• High-Volume Outbound Prospecting
• Lead Qualification Before the Handoff
• Calling Inbound Web Leads in Seconds
• Booking Meetings on a Live Call
• Renewal and Win-Back Campaigns
• Getting Past Gatekeepers and Phone Trees
• Handoff Hot Leads Off to a Live Rep
• Automated Follow-Ups for Webinar Registrants & Aged Leads (Insurance)
• Insurance Lead Qualification & Appointment Booking
• Automated Data Collection & CRM Ticketing (Insurance)
• Policy Status & Claims Assistance (Insurance)
• Overflow Call Handling & Smart Call Routing (Insurance)
• AI Schedules Appointments When Advisors Are Unavailable (Insurance)

AI approach

Retell provides a platform for building, testing, deploying, and monitoring AI voice agents for phone call centers. Their solution is described as '3rd Gen Voice AI' powered by LLMs, offering natural, human-like conversations with low latency and turn-taking capabilities. They emphasize building their own proprietary Voice AI Orchestration engine for human-quality, low-latency phone conversations at scale, and do not merely stitch together off-the-shelf APIs. They also integrate with various third-party LLMs and text-to-speech providers, allowing users to choose their preferred models.

Tech named: LLM, NLP, Proprietary Voice AI Orchestration, Proprietary turn-taking model, Streaming RAG, GPT 5.5, GPT 5.4, GPT 4.1, Claude 4.6 Sonnet, GPT 5.2, GPT 5.1, GPT 5.4 mini, GPT 5.4 nano, GPT 5, GPT 5 mini, GPT 5 nano, GPT 4.1 mini, GPT 4.1 nano, Claude 4.5 sonnet, Claude 4.5 haiku, Gemini 3.5 Flash, Gemini 3.0 Flash, Gemini 2.5 Flash, Gemini 2.5 Flash Lite, GPT Realtime 1.5

Industries served

• Healthcare
• Insurance
• Financial Services
• Logistics
• Home Services
• Debt Collection
• Retail & Consumer
• Travel & Hospitality
• Energy & Services
• E-commerce
• Performance marketing
• Software training institute
• EdTech
• Public Transit
• Real Estate
• Automotive
• Food Retailers
• Fashion Omnichannel Businesses
• Telecoms
• Emergency Services
• Utilities

What it says sets it apart

• LLM based, humanlike, voice-first conversational AI platform (3rd Gen Voice AI)
• Natural, Human-Like Conversations
• Fast Setup With Minimal Configuration
• Handles Edge Cases And Unexpected Inputs
• Supports Complex, Multi-Turn And Outbound Use Cases
• Proprietary Voice AI Orchestration Delivering Human-Quality, Low-Latency Phone Conversations At Scale
• Lowest Latency (~600ms)
• Ultra Realistic Voice built from real performance data and refined through human-guided training
• Proprietary turn-taking model that knows when to stop and when to listen
• Effortless to Use, Highly Configurable AI Phone Agent Platform
• Launch in weeks, not months
• Comprehensive Agent Testing with Built in Simulation Testing
• Continuous QA to Ensure Performance Across Edge Cases
• True pay as you go pricing model, no annual contracts required
• Enterprise-grade security, compliance, and support (HIPAA, GDPR, SOC 2 Type 1 & Type 2 certified)
• Ability to integrate with custom telephony providers via SIP
• Ability to navigate IVR systems directly
• Production-first approach, building infrastructure from the ground up for sub-second latency, natural turn-taking, interruption recovery, and agentic actions mid-call
• Delivers a customer experience indistinguishable from a human conversation
• Effortless Transition to Human Agents when needed
• AI agents can collect ~$280,000 per month without sacrificing patient trust (Medical Data Systems)
• Reduced customer support costs by over 50% (SWTCH)
• Increased scheduling NPS by 38% (Pine Park Health)
• Ability to handle 100% of inbound calls with only a 30% transfer rate (Medical Data Systems)
• AI handles 75-80% of all calls, reducing abandonment rates to 5-6% (Sunshine Loans)
• 45-50% of calls completely resolved by Retell AI without human intervention (GiftHealth)
• Ability to integrate with a wide range of CRMs, EHRs, and automation platforms
• Offers both cold and warm call transfers, including Agentic Warm Transfer for more meaningful context
• Knowledge Base feature for real-time information retrieval and reduced hallucinations
• Customizable for unique needs of various sectors (dispatch service)
• Compliance-aware outbound calling features (SOC 2 Type II, HIPAA, GDPR, PII Redaction)
• Ability to get past gatekeepers and phone trees in outbound dialing

Funding rounds we track

From the AI funding tracker — rounds as reported by the linked publications.