Retell AI
ActiveOverview
Retell AI is a platform for building, testing, deploying, and monitoring AI voice agents that automate phone calls using low-latency speech recognition, LLM-powered conversation understanding, and real-time function calling. It targets businesses handling high call volumes, such as contact centers, telehealth, and SMBs, enabling natural-sounding interactions for tasks like answering questions, scheduling appointments, and resolving issues. Key differentiators include ~600ms latency, ultra-realistic voices, proprietary turn-taking models, and no-code/low-code tools that integrate with custom LLMs like GPT-4o or Llama 3.12345
Key Features
- Low-Latency Speech Recognition - Proprietary orchestration achieves ~600ms response time for human-like interactions.
- LLM-Powered Conversations - Uses large language models for natural language understanding and dynamic flows like scheduling and objection handling.
- Real-Time Function Calling - Enables agents to execute complex tasks during calls.
- Ultra-Realistic Voices - Built from real performance data with advanced turn-taking models.
- No-Code/Low-Code Builder - Simple UI to define agent behavior without heavy engineering or scripting.
- Custom LLM Support - Upload and integrate custom models like GPT-4o or Llama 3.
- Monitoring and Analytics - Tools to deploy and monitor production-ready agents at scale.
Pricing
| Plan | Price | Includes |
|---|---|---|
| Pay-per-use | Per minute of conversation | Voice agent runtime, no fixed subscriptions mentioned. |
Platforms & Requirements
Retell AI operates as a web-based platform and API, accessible via browser for building and managing agents. It supports deployment across phone systems and applications without specified OS requirements. No notable platform limitations indicated.13
Integrations & Ecosystem
- Phone call systems
- API access
- Custom LLMs (e.g., GPT-4o, Llama 3)
- Speech models
- No-code platforms
Alternatives
| App | Difference |
|---|---|
| Bland AI | Focuses on similar voice agents but with different latency and customization options. |
| Vapi | Provides voice AI APIs emphasizing developer tools over no-code interfaces. |
| Deepgram Voice AI | Offers speech-to-text components rather than full agent orchestration platforms. |
| ElevenLabs Voice Agents | Specializes in voice synthesis with less emphasis on conversational LLM integration. |
Reputation
Retell AI is viewed positively for reducing call handling costs by up to 80% and achieving high NPS scores of 90, with hundreds of paying customers including contact centers and SMBs like Ro.45 It receives praise for ease of use, low latency, and quick deployment from months to one day.35 Some reliance on third-party LLMs and speech models is noted, though custom integrations address this.5