Retell AI
Developer API for production voice agents — the infrastructure many packaged AI receptionists are built on.
Retell AI is a developer platform for building production voice agents: speech-to-text/text-to-speech orchestration, turn-taking and interruption handling, telephony, function calling into CRMs and calendars, and batch outbound campaigns. Many packaged SMB receptionist products are built on infrastructure like Retell's.
Billing is component-level per minute with $10 in free credits and 20 concurrent calls included. It's the most flexible option in this guide — and the one that assumes you have engineers.
Pricing
~$0.07–$0.31/min — Pay-as-you-go, no base subscription: voice infrastructure $0.055/min + TTS from $0.015/min (ElevenLabs $0.04–$0.10/min) + LLM by model (from ~$0.002/min to $0.38/min for speech-to-speech models) + US telephony $0.015/min; the vendor states $0.07–$0.31/min overall. Add-ons from $0.005/min (knowledge base, denoising, guardrails). $10 free credits; 20 concurrent calls included, $8/concurrent/mo after; SMS $0.01/message; Retell numbers $2/mo.
Verified 2026-10-26 against the vendor's pricing page. Pricing changes — always confirm with the vendor before buying.
Pros & cons
Pros
- Transparent component-level pricing with free starting credits
- Production-grade voice infrastructure: low-latency turn-taking and interruption handling
- 20 concurrent calls included free — generous for the category
- Model-agnostic: choose your LLM and voice provider per cost/quality
Cons
- Requires engineering — nothing is customer-ready out of the box
- Stacked per-minute billing is hard to forecast
- Premium LLM/voice choices push costs toward the top of the vendor's own $0.07–$0.31/min range
- No done-for-you setup or human receptionists
Feature checklist
| Feature | Retell AI |
|---|---|
| Price (month-to-month) | ~$0.07–$0.31/min |
| 24/7 call answering | ✓Agents run continuously once deployed |
| Appointment scheduling | ✓Via function calling |
| SMS follow-up / texting callers | PartialVia tooling/integrations you build |
| Email follow-up | Not published |
| CRM / back-office integrations | ✓Function/tool calling, webhooks |
| Live transfer to a human | ✓SIP/Twilio transfer |
| Spanish / bilingual support | ✓Multilingual voices |
| Custom call scripts & flows | ✓Fully programmable |
| Outbound calling | ✓Batch campaigns |
| Call analytics dashboard | ✓Transcripts and call analytics |
| Industry-specific packaging | ✕ |
| Self-serve signup | ✓$10 free credits |