***

title: addInternalFiller
slug: /reference/typescript/agents/agent-base/add-internal-filler
description: Add filler phrases for a specific SWAIG function and language.
max-toc-depth: 3
---------------------

For a complete index of all SignalWire documentation pages, fetch https://signalwire.com/docs/llms.txt

[ref-agentbase]: /docs/server-sdks/reference/typescript/agents/agent-base

Add filler phrases spoken while a specific SWAIG function is executing. The AI
randomly selects from the list each time the function is invoked.

## **Parameters**

<ParamField path="functionName" type="string" required={true} toc={true}>
  Name of the SWAIG function these fillers apply to (e.g., `"next_step"`, `"check_time"`).
</ParamField>

<ParamField path="languageCode" type="string" required={true} toc={true}>
  BCP-47 language code (e.g., `"en-US"`, `"es"`, `"fr"`).
</ParamField>

<ParamField path="fillers" type="string[]" required={true} toc={true}>
  Array of filler phrases for this function and language.
</ParamField>

## **Returns**

[`AgentBase`][ref-agentbase] -- Returns `this` for method chaining.

## **Example**

```typescript {5}
import { AgentBase } from '@signalwire/sdk';

const agent = new AgentBase({ name: 'support', route: '/support' });
agent.setPromptText('You are a helpful assistant.');
agent.addInternalFiller(
  'next_step', 'en-US',
  ['Moving to the next step...', 'Great, let\'s continue...'],
);
agent.addInternalFiller(
  'next_step', 'es',
  ['Pasando al siguiente paso...', 'Continuemos...'],
);
await agent.serve();
```