Retell AI vs Ultravox
Detailed side-by-side comparison to help you choose the right tool
Retell AI
🟡Low CodeVoice AI
Retell AI is an end-to-end platform for building, deploying and monitoring voice AI agents that handle phone calls at production scale.
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Starting Price
$0.07/minUltravox
Voice AI Tools
Breakthrough real-time voice AI infrastructure that processes speech natively without ASR conversion, delivering human-like conversational agents with sub-300ms time-to-first-token latency at $0.05/minute.
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Starting Price
CustomFeature Comparison
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Retell AI - Pros & Cons
Pros
- ✓Compliance posture (SOC 2 Type II, HIPAA, PCI) is genuinely turnkey for regulated industries.
- ✓No-code flow editor lets ops teams own the agent without engineering tickets.
- ✓Latency tuning is audibly better than rolling your own STT-LLM-TTS pipeline.
Cons
- ✗Per-minute pricing can spike on unbounded outbound campaigns without budget caps.
- ✗Knowledge base ingestion is simpler than dedicated RAG platforms.
- ✗Deep customisation still requires the SDK and engineering work.
Ultravox - Pros & Cons
Pros
- ✓Speech-native architecture bypasses the ASR step, preserving tone and prosody while targeting time-to-first-token latency under 300ms for human-feeling turn-taking.
- ✓At $0.05 per minute on the managed cloud, pricing is positioned as significantly lower than OpenAI's GPT-4o Realtime API, making always-on voice agents more economically viable at scale.
- ✓Open-weight models available on Hugging Face allow self-hosting for HIPAA, data-residency, or air-gapped deployments without vendor lock-in.
- ✓First-class WebRTC, WebSocket, and SIP/Twilio telephony integrations let the same agent serve web, mobile, and inbound phone use cases without re-architecture.
- ✓Native tool-calling and function execution let agents fetch data, trigger actions, and hand off to humans as first-class primitives rather than brittle add-ons.
- ✓Transparent, developer-focused pricing with a free tier (30 minutes, 5 concurrent calls) lowers the barrier to prototyping multi-turn voice agents before committing to production spend.
Cons
- ✗Infrastructure-layer product with no drag-and-drop flow builder — teams need engineering capacity to design prompts, tools, and conversation logic.
- ✗Smaller voice and language catalog than mature TTS-first vendors like ElevenLabs, which can limit options for highly branded or exotic-language agents.
- ✗Being a newer platform, the ecosystem of community templates, integrations, and third-party tutorials is thinner than Vapi or Retell.
- ✗Self-hosting the open-weight model requires non-trivial GPU infrastructure and MLOps expertise, so the cost advantage narrows for small teams that try to run it themselves.
- ✗Enterprise features like SSO, detailed audit logs, and regional isolation are still maturing compared to established contact-center incumbents.
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