> ## Documentation Index
> Fetch the complete documentation index at: https://docs.famulor.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Engine types

> Quick overview: how Pipeline, Speech-to-Speech, and Dualplex differ — and when to choose which mode.

Famulor offers **three engine types** for your assistants’ voice stack. They mainly differ by whether **text** appears as an intermediate step in the flow — and how **latency** is traded against **controlled reasoning**.

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</div>

## 1. Pipeline (classic)

**Flow:** Speech → text (transcription) → language model → reply text → speech (TTS).

This is the **classic pipeline**: the model reasons over **text**, which you can trace and tune. That path takes a bit **more time**, but it shines when **logic, longer replies, or heavy automation** matter.

**Typical use cases:** detailed explanations, structured workflows, scenarios where you want maximum **control over wording and voice**.

## 2. Speech-to-Speech

Here the **text stage is skipped**: the model **listens** and **speaks** directly — similar to **ChatGPT’s voice mode** (the blue circle).

It is usually the **fastest** mode with the lowest perceived wait — great for a **snappy outbound caller** or short, reactive dialogs.

## 3. Dualplex

**Dualplex combines** both approaches: the system **decides what fits best** at each moment — e.g. fast turn-taking where it helps, and more “thinking room” where needed.

For **most setups**, Dualplex is a strong **default**. If you need more precision, longer answers, or finer control, switch to **Pipeline**.

<Tip>
  For technical detail, latency ranges, and tables, see [Assistant modes](/en/ai-assistants/assistant-modes). Practical tuning tips are in [AI assistant best practices](/en/ai-assistants/assistant-best-practices).
</Tip>

## Quick decision

| Goal                                                          | Lean toward          |
| ------------------------------------------------------------- | -------------------- |
| Good default, balanced                                        | **Dualplex**         |
| Maximum speed, short dialogs                                  | **Speech-to-Speech** |
| Strong reasoning, long/complex replies, full pipeline control | **Pipeline**         |