5 products compared
Voice agent platforms are the building blocks behind AI phone calls. Developers and agencies use them to create agents that answer or place calls, connected to phone numbers, a language model and a voice. They are usually billed per minute of talk time.
A per-minute rate often covers only part of the cost. Some platforms bill the model, the voice and the phone line separately, so the total can be well above the headline number. Each listing shows what the vendor publishes.
Prices checked up to 16 October 2026.
5 of 5 products. Feature filters only match features confirmed on the vendor’s own site.
Bland AI · Voice agents
Platform for building AI phone agents that handle inbound and outbound calls, plus SMS and web. Runs on its own models and bills per minute of talk time with a platform fee on higher tiers.
PolyAI · Voice agents
Enterprise voice agent platform for customer service calls, also covering chat, SMS and messaging. Agents can be built in its self-serve Agent Studio or deployed with PolyAI's team.
Retell AI · Voice agents
Platform for building AI voice agents that answer and place phone calls, with chat and SMS agents too. Usage is billed per minute, split into voice infrastructure, LLM, voice and telephony components.
Synthflow AI · Voice agents
Voice AI platform for building agents that handle inbound and outbound calls, integrated with contact-center systems and CRMs. Sold on enterprise contracts scoped by call volume and integrations.
Vapi · Voice agents
Developer platform and API for building voice agents that make and receive phone calls or run in web apps. Vapi charges a hosting fee per minute and passes through model, voice and transcription costs.
The cheapest published paid option for each product, in the vendor’s own unit. Read the billing model before comparing two rows.
| Product | Free plan | Starts at | Billing model | Usage charges | Checked |
|---|---|---|---|---|---|
| Bland AIOfficial pricing | Not verified | From $0.14 per minute talk time, telephony extra | subscription + per minute | Talk time (Start): $0.14 per minuteTransfer time (Start): $0.05 per minute | 16 October 2026 |
| PolyAIOfficial pricing | Not verified | Contact sales | Custom quote | None published | 16 October 2026 |
| Retell AIOfficial pricing | Not verified | From $0.07 per minute, all components | per minute + usage-based + per call + usage credits | Retell Voice Infra: $0.055 per minuteVoice: Retell Platform Voices: $0.015 per minute | 16 October 2026 |
| SynthflowOfficial pricing | Not verified | From $30,000/year | subscription | None published | 16 October 2026 |
| VapiOfficial pricing | Not verified | $0.05 per minute hosting, plus model, voice and telephony | subscription + per minute + usage-based | Vapi hosting: $0.05 per minuteHIPAA compliance add-on: $2,000 per month | 16 October 2026 |
Confirmed on the vendor’s site Vendor says it is not offered Not verified (not the same as no)
| Feature | Bland AI | PolyAI | Retell AI | Synthflow | Vapi |
|---|---|---|---|---|---|
| Phone calls | Yes | Yes | Yes | Yes | Yes |
| Voice conversation | Yes | Yes | Yes | Yes | Yes |
| Developer API | Yes | Yes | Yes | Yes | Yes |
| Integrations | Yes | Yes | Yes | Yes | Yes |
| Books appointments | Yes | Not verified | Yes | Yes | Yes |
| Multiple languages | Yes | Yes | Yes | Yes | Yes |
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