Category
Voice AI agents: what they are and who makes them
developer platforms with pass-through components, all-in agent builders, infrastructure and toolkits, enterprise contact-center platforms: Retell AI, Vapi, ElevenLabs Agents through Pipecat Cloud.
Types of voice AI agents
Developer platforms with pass-through components
Vapi and Retell AI charge a platform fee per minute, then bill the model, voice and phone provider on top. You tune each part and can swap vendors. The final price per minute is a sum you calculate yourself, which suits engineering teams better than a service desk manager who wants one number.
All-in agent builders
Bland bundles model, transcription and voice into one per-minute rate, and ElevenLabs Agents sells call minutes inside monthly plans. The bill is easier to forecast, though you accept the vendor's chosen components and fewer places to swap parts out when a particular voice or model falls short.
Infrastructure and toolkits
LiveKit and Deepgram supply the plumbing: realtime transport, agent hosting, speech models and a voice agent API. You write the conversation logic yourself. This route gives the most control and the most engineering work, and it fits product teams embedding voice in their own app.
Enterprise contact-center platforms
Parloa, PolyAI and Synthflow's enterprise tier sell managed deployments for banks, insurers, hotels and retailers. Prices are scoped per project, and the vendor's engineers help build the flows. They fit large call volumes and procurement reviews, not a quick trial on a Friday.
Facts at a glance
| Tool | Publisher | Based in | Access |
|---|---|---|---|
| Retell AI | Retell AI | United States | Trial + API |
| Vapi | Vapi, Inc. | United States | Trial + API |
| ElevenLabs Agents | Eleven Labs Inc. | United States | Free tier + API |
| Bland | Bland AI | United States | Trial + API |
| Synthflow | AgentFlow AI GmbH | Germany | Paid + API |
| LiveKit | LiveKit | United States | Free tier + API |
| Parloa | Parloa | Germany | Paid + API |
| PolyAI | PolyAI Ltd | United Kingdom | Trial + API |
| Deepgram Voice Agent API | Deepgram | United States | Trial + API |
| Ultravox | Ultravox | Not stated on the pages read | Trial + API |
| Pipecat Cloud | Daily | Not stated on the pages read | Paid + API |
