***

title: Variables
sidebarTitle: Variables
description: Dynamic values for personalization and data flow.
--------------------------------------------------------------

Variables let you insert dynamic values into prompts, conditions, and API calls. Use them to personalize conversations, pass data between systems, and create dynamic flows.

***

## Syntax

```
{{variable_name}}
```

Variables are replaced with actual values at runtime.

***

## Variable Types

| Type             | Source             | Example                                 |
| ---------------- | ------------------ | --------------------------------------- |
| **System**       | Platform-provided  | `{{caller_phone}}`, `{{call_duration}}` |
| **User Defined** | You create         | `{{company_name}}`, `{{promo_code}}`    |
| **API**          | From API responses | `{{customer_name}}`, `{{account_tier}}` |

***

## System Variables

| Variable             | Description             |
| -------------------- | ----------------------- |
| `{{caller_phone}}`   | Caller's phone number   |
| `{{call_time}}`      | When call started       |
| `{{call_duration}}`  | Elapsed seconds         |
| `{{call_direction}}` | "inbound" or "outbound" |
| `{{agent_id}}`       | This agent's ID         |
| `{{call_id}}`        | Unique call identifier  |

***

## Default Values

Handle missing variables with fallbacks:

```
Hello {{customer_name|there}}!
```

If `customer_name` is empty → "Hello there!"

***

## Implementation

Variables work in both agent types with slight differences in how they're configured.

<CardGroup cols={2}>
  <Card title="Single Prompt" icon="message" href="/atoms/atoms-platform/single-prompt-agents/configuration-panel/variables">
    Variables in Configuration Panel
  </Card>

  <Card title="Conversational Flow" icon="diagram-project" href="/atoms/atoms-platform/conversational-flow-agents/workflow-tab/variables">
    Variables in Workflow Tab
  </Card>
</CardGroup>