Overview
Retell AI is a platform for building, deploying and monitoring AI voice agents that handle inbound and outbound phone calls, with chat and SMS channels. It includes a visual call-flow builder, knowledge bases, appointment booking, batch outbound calling, call transfer and post-call analytics. It is developer-friendly with APIs and SDKs, and lists use cases such as AI receptionist, answering service and appointment setting.
Label: Vendor-described — Captured from the vendor's own materials. Not independently verified.
Best for
- Businesses wanting an AI receptionist or appointment-booking phone agent
- Developers and agencies building inbound/outbound voice agents via API
Key features
- Voice agents for inbound and outbound calls
- Appointment booking, lead qualification and warm transfer
- No-code flow builder plus developer APIs and SDKs
- Integrations with Twilio, HubSpot, GoHighLevel, n8n, Make
- Post-call analysis and AI quality assurance
- Batch outbound campaigns with branded caller ID
What it does
- Inbound and outbound AI voice agents
- Drag-and-drop call flow builder
- Appointment booking and live transfer to humans
- Batch outbound calling campaigns
- Knowledge base answers
- Post-call analysis and QA review
Use cases
- Answer missed calls and book jobs while you're on site — For a custom setup: build your own AI voice agent with appointment booking and live transfer, billed per minute.
Drawbacks & cautions
- Per-minute cost varies with chosen LLM and voice models
- Extra concurrency, knowledge bases beyond 10 and phone numbers are billed monthly
- Telephony billing continues after transfer to a human
What users say
Across G2 and Trustpilot, reviewers are strongly positive about Retell's ease of setup, natural-sounding voices and API. The main complaints are cost at scale, a learning curve for complex agents, and occasional latency or slow support.
What people like
- Intuitive setup; agents can be built quickly g2.com, ca.trustpilot.com
- Natural, human-like voices and conversation g2.com, ca.trustpilot.com
- Solid API and integrations, including CRM connections g2.com, ca.trustpilot.com
- Frequent product updates and reliable uptime ca.trustpilot.com
Common complaints
- Costs climb at higher call volumes g2.com, ca.trustpilot.com
- Learning curve for advanced flows and prompt tuning g2.com, ca.trustpilot.com
- Occasional response latency interrupts conversation flow ca.trustpilot.com
- Support can be slow to reach for some users ca.trustpilot.com
Scores are shown as each site published them on the date checked. They come from those sites' reviewers, not from us, and they never affect our rankings. Ratings based on fewer than 10 reviews are left out. The summaries are our own words, gathered Oct 22, 2026; follow the links to read the reviews.
Alternatives
- ElevenLabs — AI voice generation, voice cloning, dubbing, transcription and music via app and API
- Fliki — Turn scripts, blog posts and slides into narrated videos with AI voices, avatars and translation
- Murf AI — AI voice generator for voiceovers, dubbing and text-to-speech API
- My AI Front Desk — AI receptionist that answers calls 24/7, books appointments, texts and follows up with leads
Evidence
| Fact | Label | Source | Observed |
|---|---|---|---|
| capabilities | Vendor-described | www.retellai.com | Oct 17, 2026 |
| hasApi | Vendor-described | docs.retellai.com | Oct 17, 2026 |
| integrations | Vendor-described | www.retellai.com | Oct 17, 2026 |
| pricing | Vendor-described | www.retellai.com | Oct 17, 2026 |
Spot something wrong? Send a correction.