> Fetch clean Markdown by appending `.md` to any page URL under https://signalwire.com/docs or requesting it with the HTTP header `Accept: text/markdown`. The root index at https://signalwire.com/docs/llms.txt lists the available documentation indexes.

# Inworld

> Learn how to use Inworld's expressive, multilingual TTS models with SignalWire AI Voice applications.

Inworld is a text-to-speech engine offering high-quality, expressive voices across many languages.

## Models

SignalWire supports two Inworld models.
See [Inworld's model documentation](https://docs.inworld.ai/tts/tts-models) for more detail.

| Model                  | Description                                                                      |
| ---------------------- | -------------------------------------------------------------------------------- |
| `inworld-tts-1.5-mini` | Faster, lower-cost model, suited for high-volume, latency-sensitive applications |
| `inworld-tts-1.5-max`  | Higher-quality model, suited for expressive, character-driven, and premium reads |

> **Info**
>
> Defaults to `inworld-tts-1.5-mini` when used with [AI agents](/docs/swml/reference/ai); otherwise it
> defaults to `inworld-tts-1.5-max`. Set a model explicitly to override this.

## Voices

Inworld provides a large library of expressive voices across many languages.
A voice's name is its voice ID — for example, `Lauren` becomes `inworld.Lauren` in the
[voice string](#usage).

> **Warning**
>
> Only Inworld's built-in voices are supported. Cloned and custom voices do not work — you must use
> one of the default voice IDs that Inworld provides.

Preview the voices and find their IDs in Inworld's documentation:

#### [Inworld TTS Playground](https://docs.inworld.ai/tts/tts-playground)

Preview Inworld voices and models in the browser.

#### [Inworld TTS docs](https://docs.inworld.ai/tts/tts)

Reference for voices, models, and languages.

## Languages

Inworld supports the following languages:

| Language           | Code |
| :----------------- | :--- |
| English            | `en` |
| Arabic             | `ar` |
| Chinese (Mandarin) | `zh` |
| Dutch              | `nl` |
| French             | `fr` |
| German             | `de` |
| Hebrew             | `he` |
| Hindi              | `hi` |
| Italian            | `it` |
| Japanese           | `ja` |
| Korean             | `ko` |
| Polish             | `pl` |
| Portuguese         | `pt` |
| Russian            | `ru` |
| Spanish            | `es` |

Refer to the [Inworld TTS docs](https://docs.inworld.ai/tts/tts)
for the most up-to-date reference to supported languages and voices.

## Usage

A voice identifier string has three parts: the `inworld` engine code, a voice ID, and an optional model.

**Format**: `inworld.<voiceId>:<model>`

* `voiceId` (required): an Inworld voice name (for example, `Lauren`); see [Voices](#voices).
* `model` (optional): one of the [models](#models) above. If you omit it, a default model is used.

**Examples**:

```text
inworld.Lauren:inworld-tts-1.5-mini
inworld.Brian:inworld-tts-1.5-max
inworld.Asuka:inworld-tts-1.5-mini
```

You can also set the model with the separate
[`model`](/docs/swml/reference/ai/languages#use-voice-strings)
parameter of the [`languages`](/docs/swml/reference/ai/languages) SWML method
instead of appending `:model` to the voice string:

```yaml
languages:
- name: English
  code: en-US
  voice: inworld.Lauren
  model: inworld-tts-1.5-mini
```

---

## Build with Inworld on SignalWire

### Create a Space and add credit

If you don't have one yet, you'll need to
[create a SignalWire Space](/docs/platform/signing-up-for-a-space).
Be sure to add some credit to test with.

### Add a new Resource

Navigate to the **Resources** tab in your [SignalWire Dashboard](https://my.signalwire.com) and click **+ Add New** to create a new Resource.

### Create a SWML Script

From the Resources menu, select **SWML Script**.
Name it something fun and recognizable.
Ours is titled Inworld Wizard.

Next, paste the following starter script into the text box, and hit <kbd>Save</kbd>:

```yaml
version: 1.0.0
sections:
  main:
  - ai:
      prompt:
        text: |
          You're Lauren, a voice from Inworld's TTS engine!
          Introduce yourself, and have a conversation about programmable unified communications on the SignalWire platform.
      languages:
      - name: English
        code: en-US
        voice: inworld.Lauren:inworld-tts-1.5-mini
```

### Buy and assign a phone number

Navigate to the **Phone Numbers** section of the Dashboard's left sidebar menu.

Purchase a phone number and assign it to the desired SWML script.

In the Dashboard, open **Phone Numbers** > **Purchased**, select the number, and open its edit page. Under **Inbound Call Settings**, select **+ Assign Resource**, choose the SWML script, and save the settings.

### Give it a call!

Call the number you just assigned to chat with your new AI voice application on the phone.

## Next steps with SWML

Now you've deployed your very first SignalWire voice AI application using Inworld voices.
Next, dive deeper into SWML to explore its capabilities!

#### [Methods reference](/docs/swml)

Documentation for all SWML methods

#### [AI in SWML](/docs/swml/guides)

Build advanced AI applications using SignalWire Markup Language

#### [Guides](/docs/swml/guides)

SWML guides and demo applications

> Text-to-speech