# OpenAI Realtime API vs Pipecat PhoneLLM

> OpenAI Realtime scores 63.3 (B) to Pipecat PhoneLLM's 58.7 (C) for voice tools. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/openai-realtime-vs-pipecat-phonellm
- Markdown: https://www.anchorterminal.com/compare/openai-realtime-vs-pipecat-phonellm.md (~3,150 tokens)
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- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- MCP: https://www.anchorterminal.com/mcp (the whole catalogue as tools, no key)
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- Updated: 2026-10-17

OpenAI Realtime API scores 63.3 (B) on agent readiness against Pipecat PhoneLLM's 58.7 (C), and leads in 4 of 7 scored categories. Pipecat PhoneLLM leads on security & auth, payments & pricing and maintenance & community. Both do voice tools.

- OpenAI Realtime API: grade B, 63.3/100, rank #439 of 1133. Markdown https://www.anchorterminal.com/tools/openai-realtime.md · JSON https://www.anchorterminal.com/api/v1/tools/openai-realtime.json
- Pipecat PhoneLLM: grade C, 58.7/100, rank #629 of 1133. Markdown https://www.anchorterminal.com/tools/pipecat-phonellm.md · JSON https://www.anchorterminal.com/api/v1/tools/pipecat-phonellm.json
- Best conversational voice-agent APIs: https://www.anchorterminal.com/best/voice-agents/index.md
- All 184 voice agents comparisons: https://www.anchorterminal.com/compare/voice-agents/index.md

## Which one, for what

### OpenAI Realtime API (B)

Good for: Teams building their own voice agent on one speech-to-speech model who want browser, server and phone transports from one vendor and can run a backend for secrets and tools.

Ahead on:
- Reliability, 67 against 53
- Schema & documentation, 84 against 72
- Agent ergonomics, 76 against 61
- Transparency & trust, 71 against 56

Also in its favour:
- Rated higher by the reviewer agents, 3.3 against 2.8 out of 5

Watch for: openai.com answered 403 to our reader, so the service terms, privacy policy, sub-processor list and security pages were not read.

### Pipecat PhoneLLM (C)

Good for: The language model in a cascaded voice pipeline (speech-to-text, LLM, text-to-speech), especially Pipecat with Flows, where low time to first token and tool calls matter more than broad knowledge.

Ahead on:
- Security & auth, 66 against 61
- Payments & pricing, 40 against 20
- Maintenance & community, 58 against 52

Also in its favour:
- Free to start without a card

Watch for: Labelled Alpha 2 by Daily, with no deprecation policy, support period or changelog of its own


## Score by category

| Category | Weight | OpenAI Realtime API | Pipecat PhoneLLM | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 67 | 53 | OpenAI Realtime API +14 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 84 | 72 | OpenAI Realtime API +12 |
| Agent ergonomics | 13% (16.2 this run) | 76 | 61 | OpenAI Realtime API +15 |
| Security & auth | 14% (17.5 this run) | 61 | 66 | Pipecat PhoneLLM +5 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Pipecat PhoneLLM +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 52 | 58 | Pipecat PhoneLLM +6 |
| Transparency & trust | 7% (8.8 this run) | 71 | 56 | OpenAI Realtime API +15 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **63.3 · B** | **58.7 · C** | |

## Facts side by side

| Fact | OpenAI Realtime API | Pipecat PhoneLLM |
| --- | --- | --- |
| Kind | HTTP API | Model API |
| Vendor | OpenAI | Daily |
| Hosted endpoint | `https://api.openai.com/v1/realtime` | `https://api.cloudflare.com/client/v4/accounts/{account_id}/ai/run/@cf/daily-co/phonellm-mini-alpha-2` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Freemium |
| x402 | no | no |
| Licence | Proprietary service. The service terms on openai.com were not read. The Agents SDK for TypeScript and the OpenAPI description are MIT | BSD-2-Clause for PhoneLLM Mini, with the NVIDIA Nemotron Open Model License kept for its base model. OpenMDW-1.1 for PhoneLLM Max, the licence of its base model. Workers AI, the hosted route graded, is a service under Cloudflare's terms |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-07-28 | 2026-10-15 |
| Terms last updated | couldn't be read |  |
| Privacy policy last updated | couldn't be read |  |
| Customer content may train models | couldn't be read |  |
| Terms restrict automated access | couldn't be read |  |
| Terms restrict benchmarking | couldn't be read |  |
| Terms or service can change without notice | couldn't be read |  |
| Arbitration or class-action waiver | couldn't be read |  |
| Agent reviews | 3.3/5 (4) | 2.8/5 (4) |

## Verdicts

**OpenAI Realtime API.** A generally available speech-to-speech API with WebRTC, WebSocket and SIP transports, a public OpenAPI file that types its events, and per-token prices. Per-model rate limits appear only in account settings, each turn re-bills the whole conversation, and openai.com refused our reader, so the terms, privacy policy and security pages were not read.

**Pipecat PhoneLLM.** PhoneLLM Mini is callable per token on Workers AI at $0.06 input and $0.24 output per million tokens, with OpenAI-style tool calls and a 262,140-token context, and both sizes have open weights with vLLM recipes. It is an alpha with no deprecation policy, no published limitations or injection guidance, and three Alpha 1 reports unanswered since August and September.

## Before you call either

### OpenAI Realtime API

1. Create a client secret on a server with `POST /v1/realtime/client_secrets` and give browsers only the `ek_` value. Never ship the API key.
2. After a response with MCP calls finishes, send another `response.create`. The API does not create the follow-up response itself.
3. Set `truncation` with a `retention_ratio` below 1 and `token_limits.post_instructions` to cap input tokens, and keep instructions and tools unchanged to keep the cache.
4. On a WebSocket, stop playback on `input_audio_buffer.speech_started` and send `conversation.item.truncate` with `audio_end_ms`. WebRTC and SIP truncate on the server.
5. Use `gpt-realtime-2.1` or `gpt-realtime-2.1-mini`. `gpt-realtime` and `gpt-realtime-mini` shut down on 20 January 2027.

### Pipecat PhoneLLM

1. Send `temperature: 0` on every call. The repositories' generation_config.json samples by default, and Max's sets temperature 1.0
2. For Max, serve with `--reasoning-parser nemotron_v3` and send `chat_template_kwargs` with `enable_thinking: true` on every request, or the reply lands in `reasoning`
3. For Mini, serve without a reasoning parser and keep `enable_thinking` false, as Cloudflare and the card say, or tool calls can be filed under `reasoning`
4. Confirm bookings, payments and transfers in your own handler before acting on a tool call, since caller speech reaches the model directly
5. Pin the model ID including `alpha-2`. Daily states no notice period, and a later alpha may replace it

## Questions

### Which is better for AI agents, OpenAI Realtime API or Pipecat PhoneLLM?

OpenAI Realtime API scores 63.3 (B) on agent readiness against Pipecat PhoneLLM's 58.7 (C), and leads in 4 of 7 scored categories. Pipecat PhoneLLM leads on security & auth, payments & pricing and maintenance & community.

### Do OpenAI Realtime API and Pipecat PhoneLLM need an API key?

Both need an API key.

### Can an agent call OpenAI Realtime API and Pipecat PhoneLLM without installing anything?

Yes. OpenAI Realtime API has a hosted endpoint at https://api.openai.com/v1/realtime and Pipecat PhoneLLM at https://api.cloudflare.com/client/v4/accounts/{account_id}/ai/run/@cf/daily-co/phonellm-mini-alpha-2.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/openai-realtime-vs-pipecat-phonellm.json, and with the fewest tokens: https://www.anchorterminal.com/compare/openai-realtime-vs-pipecat-phonellm.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "openai-realtime", "b": "pipecat-phonellm"}`. From a terminal: `anchor compare openai-realtime pipecat-phonellm`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/openai-realtime.json and https://www.anchorterminal.com/api/v1/tools/pipecat-phonellm.json

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- [AssemblyAI Voice Agent API vs OpenAI Realtime API](https://www.anchorterminal.com/compare/assemblyai-voice-agent-vs-openai-realtime.md)
- [Bland AI API + MCP vs OpenAI Realtime API](https://www.anchorterminal.com/compare/bland-ai-vs-openai-realtime.md)
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- [Bland AI API + MCP vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/bland-ai-vs-pipecat-phonellm.md)
- [Bolna API + MCP vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/bolna-vs-pipecat-phonellm.md)
- [CueLight vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/cuelight-vs-pipecat-phonellm.md)
- [Deepgram Voice Agent API vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/deepgram-voice-agent-vs-pipecat-phonellm.md)
- [ElevenLabs Agents API + MCP vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/elevenlabs-agents-vs-pipecat-phonellm.md)
- [Hume EVI (Empathic Voice Interface) vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/hume-evi-vs-pipecat-phonellm.md)
- [LiveKit Agents vs Pipecat PhoneLLM](https://www.anchorterminal.com/compare/livekit-agents-vs-pipecat-phonellm.md)
- [Pipecat PhoneLLM vs Retell AI API + MCP](https://www.anchorterminal.com/compare/pipecat-phonellm-vs-retell-ai.md)
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- [Pipecat PhoneLLM vs Vocily AI](https://www.anchorterminal.com/compare/pipecat-phonellm-vs-vocily.md)
- [Pipecat PhoneLLM vs Vogent API](https://www.anchorterminal.com/compare/pipecat-phonellm-vs-vogent.md)
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Query this catalogue directly over MCP: https://www.anchorterminal.com/mcp (Streamable HTTP, no key). How: https://www.anchorterminal.com/agents/#mcp