Retell AI Review, Pricing & Alternatives (2026)

Retell AI began as a five-person team accepted into Y Combinator in November 2023, then launched publicly in February 2024 through Hacker News and Product Hunt. The company raised a $4.6 million seed round in May 2024, backed by Alt Capital and angel investors; TechCrunch reported $4.53 million raised and hundreds of paying customers that month. Retell’s platform lets businesses build voice agents for phone and web conversations, with templates, APIs, transcripts, analytics, webhooks, simulation tools, and transfers. Its pay-as-you-go plan has no platform fee or minimum commitment, lists voice pricing at $0.07 to $0.31 per minute, and includes 20 concurrent calls. Retell later reported $40 million in annualized revenue in 2025 with a 25-person team, followed by $80 million by December 2025.

A typical Retell workflow begins with a prebuilt template or new agent, followed by configuration of prompts, conversation flows, knowledge sources, tools, transfers, voice settings, and language models. Teams can connect a web call or phone number, then review behavior in Playground, simulation, batch, web, or phone tests. Text tests are billed per message, while web and phone tests use applicable production rates. Before launch, developers can test webhook and custom-function payloads, configure fallback behavior, and revise agent versions. In production, call transcripts, analytics, filters, alerts, and quality tools support monitoring. Agents can also hand calls to staff, use knowledge bases, send SMS, and apply safety guardrails. Retell’s platform supports GPT, Claude, Gemini, ElevenLabs, Cartesia, and other voice or model options.

Retell AI combines a voice-orchestration engine with large language models, speech recognition, text-to-speech, telephony, and agentic tools. Its model menu includes OpenAI GPT, Anthropic Claude, Google Gemini, and speech-to-speech GPT Realtime options, while voice providers include ElevenLabs, Cartesia, Minimax, Fish, OpenAI, and Inworld. In December 2025, Retell added GPT-5.2, Gemini 3 Flash, and Claude 4.5 Haiku and Sonnet. February 2026 brought hard-stop safety guardrails, webhook and function testing, transcription auto-failover, batch testing through an API, and automatic migration from deprecated models such as Claude 3.7 Sonnet to Claude 4.5 Sonnet. In August 2026, GPT-5.6 and GPT Realtime 2.1 became available in the agent builder, alongside improved transfer handling and Spanish transcription support.

Retell’s practical cost is metered rather than subscription-led. Pay-as-you-go voice pricing is listed at $0.07 to $0.31 per minute, with no platform fee, contract, or minimum commitment. The bill can include $0.055 per minute for voice infrastructure, model usage, text-to-speech, telephony, and selected add-ons. A representative configuration using GPT 5.1, a platform voice, and a Retell U.S. number totals $0.125 per minute before extras. Telephony is listed at $0.015 per minute, while bring-your-own SIP avoids Retell’s telephony charge. Twenty concurrent calls are included; additional capacity costs $8 per call monthly. Phone numbers cost $2 monthly, and knowledge bases beyond the first 10 cost $8 each. Testing is also billed at production rates, so pilots need a usage allowance.

Retell AI’s main limitation is cost complexity: its $0.07 to $0.31 headline range excludes some telephony and add-on charges, and testing is billed at production rates rather than through a free sandbox. Vapi is a strong alternative for developer-led voice orchestration, while Bland AI offers a more focused phone-agent product; ElevenLabs Conversational AI may appeal more to teams prioritizing voice quality, since TechCrunch’s 2024 test found Retell’s synthetic voice less realistic than ElevenLabs and OpenAI’s. Retell counters with broader workflow tooling, including simulations, webhooks, analytics, transfers, versioning, guardrails, and 20 included concurrent calls. Its enterprise plan adds custom terms, SSO, access controls, and dedicated support, but requires a sales process. Pick Retell for configurable production workflows and metered experimentation, not flat pricing or self-hosting.