Retell AI

Worth knowing before you sign

• · You build and maintain the agent yourself. The quickstart walks you through creating an account, picking a single-prompt or conversation-flow agent, choosing "Build from scratch to build everything yourself" or a template, writing the prompt, wiring the tools, buying a number and deploying. There is no managed setup service in the published pricing.
• · There is no single per-minute price. The advertised "$0.07-$0.31/min" is Retell voice infrastructure ($0.055/min) plus a TTS rate plus an LLM rate, and telephony ($0.015/min for US Twilio) is charged on top of that range.
• · Model choice moves the bill by more than 50x: LLM alone runs from $0.003/minute (GPT 5 nano) to $0.345/minute (GPT Realtime speech-to-speech).
• · Concurrency beyond the free 20 costs "$8.00/Concurrency/month" per additional concurrent call.
• · Knowledge bases beyond the first 10 cost "$8.00/Knowledge Base/month", Retell phone numbers "$2.00/month", verified numbers "$10.00/Phone number/month" and Retell SMS "$20.00/month" — these are subscription items billed at month-end, not deducted from prepaid credits.
• · You are billed for the whole connected call including silence and hold time, because the speech-to-text engine stays active.
• · A payment method is required before you can purchase a phone number, even though the $10 trial credit needs none.
• · Bot only — Retell supplies no human agents or live-answer fallback.
• · Language coverage is provider-dependent: a language must be supported by both a TTS provider and an ASR provider, and the docs state the dashboard language picker, not the docs table, is "the live source of truth". The list captured here is the set of languages supported by at least one Retell TTS provider.
• · Founding year is not published on the site, docs or terms.