Skip to the call
Fluid 1

Fluid

Reliable voice-to-voice.

It knows when to talk.

  1. CallerI’d like to change my bank details, I switched banks last month.
  2. FluidListensMhm.
  3. FluidStopsSure. What’s the new IBAN? You can read it out slowly and I’ll note it.
  4. CallerIt’s DE89 3704 0044 0532 0130 0, and the name on it is
  5. FluidSpeaks upSorry, a digit is missing.
  6. CallerOh, right. DE89 3704 0044 0532 0130 00.
  7. FluidWord for wordBy confirming, you authorise us to collect payments from this account by direct debit.
  8. CallerYes, I confirm.

Frontier-level on τ²-bench.

Fluid by voice scores within five points of the same frontier model in chat.

All tasks
84%89%
Airline
86%86%
Retail
76%82%
Telecom
90%98%

τ²-bench v2, English, 150 tasks, one attempt each, spoken with tau2’s simulated customer in its two accented caller personas. Frontier model: Claude Opus 5.5 in both. Measured in November 2026.

Fluid talks, any model thinks.

Use the newest frontier model the day it ships.

Built for real calls.

OpenAI Live compatible.

client = AsyncOpenAI(
    api_key=os.environ["KUGELAUDIO_API_KEY"],
    base_url="https://api.kugelaudio.com/v1",
)
async with client.live.connect() as connection:
    await connection.session.start(session={
        "model": "fluid-1",
        "instructions": instructions,
        "audio": {"output": {"voice": "973"}},
    })
Read the guide

Pricing

€0.05per minute

€0.0595 including 19% German VAT

Back-office model costs are not included.

Need volume pricing or on-premise?

Questions

What is Fluid 1?

Fluid 1 is KugelAudio’s speech-to-speech model for voice agents. It hears your customer, answers in a natural voice and hands what it can’t answer to your backend.

Can I use my own model and tools?

Yes. Your backend answers with any model you choose and runs your tools. Or let us run the model, and keep only the tools on your side.

How do I move from OpenAI Live?

Fluid follows the OpenAI Live protocol. Point the official OpenAI SDK at Kugel’s address, use your Kugel key and set the model to fluid-1.

Does it work on the phone?

Yes. Fluid takes phone audio at 8 kHz as well as 16 and 24 kHz audio from apps and browsers, and answers in the same format.

How is it billed?

€0.05 per minute of conversation, billed by the second, from the first audio until the session ends. A model you run in your own backend is billed by its provider.

Hear it yourself.