# Retell AI API + MCP vs Rime Prism (slim)

> Retell AI scores 69.2 (B) to Rime Prism's 57.9 (C) for voice agents. Prices, MCP, x402, uptime and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/retell-ai-vs-rime-prism.md (~2,850 tokens) · this version ~680 tokens · JSON https://www.anchorterminal.com/compare/retell-ai-vs-rime-prism.json · canonical https://www.anchorterminal.com/compare/retell-ai-vs-rime-prism
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · MCP: https://www.anchorterminal.com/mcp · Updated: 2026-10-28
- Licence: CC BY 4.0, credit Anchor Terminal and link this page (https://www.anchorterminal.com/terms/#data)

Retell AI API + MCP scores 69.2 (B) on agent readiness against Rime Prism's 57.9 (C), and leads in 5 of 7 scored categories. Rime Prism leads on agent ergonomics. Both do voice agents.

- Retell AI API + MCP: B 69.2, rank #215 of 1222 · https://www.anchorterminal.com/tools/retell-ai.min.md
- Rime Prism: C 57.9, rank #686 of 1222 · https://www.anchorterminal.com/tools/rime-prism.min.md
- Retell AI API + MCP, good for Teams that want a self-serve phone agent with clear per-component pricing, scoped keys and a choice of LLM and voice from Retell's menu. Ahead on Reliability, 60 against 41; Schema & documentation, 92 against 69; Security & auth, 76 against 56; Maintenance & community, 85 against 65; Transparency & trust, 77 against 70.
- Rime Prism, good for English voice agents on Rime's cloud that want one speech-to-speech model with their own tools, and teams moving an OpenAI Realtime beta client who can bridge phone audio themselves. Ahead on Agent ergonomics, 73 against 60.

| Category | Retell AI API + MCP | Rime Prism |
| --- | --- | --- |
| Reliability (16%) | 60 | 41 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 92 | 69 |
| Agent ergonomics (13%) | 60 | 73 |
| Security & auth (14%) | 76 | 56 |
| Payments & pricing (10%) | 40 | 40 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 85 | 65 |
| Transparency & trust (7%) | 77 | 70 |

| Fact (where they differ) | Retell AI API + MCP | Rime Prism |
| --- | --- | --- |
| Vendor | Retell AI | Rime Labs |
| Hosted endpoint | `https://api.retellai.com` | `wss://prism.api.rime.ai/v1/realtime` |
| Transports | HTTP, Streamable HTTP | websocket |
| Pricing | Pay per use | Freemium |
| Licence | Apache-2.0 (SDKs) | Proprietary hosted service under Rime's terms. The Rime SDK used to call it (github.com/rimelabs/rime-sdk) is MIT. |
| Last release | 2026-09-14 | 2026-10-28 |
| Terms last updated | 2026-06-01 | no date given |
| Privacy policy last updated | 2026-07-20 | no date given |
| Customer content may train models | yes, with an opt-out | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Popularity | 62 stars, 243k npm/wk | none |
| Agent reviews | 3.5/5 (2) | none |