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

# Variable Values

## Overview

Use dynamic variables in the system prompt or any message in the dashboard with curly braces (e.g., `{name}`).

To set values, make a phone call request through the API and set `assistantOverrides`. You cannot set variable values directly in the dashboard.

For example, set the assistant's first message to "Hello, `{name}`!" and assign `name` to `Akash` by passing `assistantOverrides` with `variableValues`:

```json theme={null}
{
  "variableValues": {
    "name": "Akash"
  }
}
```

## Using dynamic variables in a phone call

<Steps>
  <Step title="Prepare Your Request">
    Create a JSON payload with these key-value pairs:

    * **`assistantId`**: Replace `"your-assistant-id"` with your assistant's actual ID.
    * **`assistantOverride`**: Customize your assistant's behavior.
      * **`variableValues`**: Include dynamic variables in the format `{ "variableName": "variableValue" }`. Example: `{ "name": "John" }`.
    * **`customer`**: Represent the call recipient.
      * **`number`**: Replace `"+1xxxxxxxxxx"` with the recipient's phone number (E.164 format).
    * **`phoneNumberId`**: Replace `"your-phone-id"` with your registered phone number's ID. Find it on the [Phone number](https://dashboard.callhq.ai/phone-numbers) page.
  </Step>

  <Step title="Send the Request">
    Send the JSON payload to the `/call/phone` endpoint using your preferred method (e.g., HTTP POST request).

    ```json theme={null}
    {
      "assistantId": "your-assistant-id",
      "assistantOverrides": {
        "variableValues": {
          "name": "Akash"
        }
      },
      "customer": {
        "number": "+91xxxxxxxxx"
      },
      "phoneNumberId": "your-phone-id"
    }
    ```
  </Step>
</Steps>

<Note>
  Ensure `{variableName}` is included in all prompts where needed.
</Note>

## Default Variables

These variables are automatically filled based on the current (UTC) time, so you don't need to set them manually in `variableValues`:

| Variable            | Description                 | Example              |
| ------------------- | --------------------------- | -------------------- |
| `{now}`             | Current date and time (UTC) | Jan 1, 2024 12:00 PM |
| `{date}`            | Current date (UTC)          | Jan 1, 2024          |
| `{time}`            | Current time (UTC)          | 12:00 PM             |
| `{month}`           | Current month (UTC)         | January              |
| `{day}`             | Current day of month (UTC)  | 1                    |
| `{year}`            | Current year (UTC)          | 2024                 |
| `{customer.number}` | Customer's phone number     | +1xxxxxxxxxx         |
| `{customer.X}`      | Any other customer property |                      |

## Advanced date and time usage

You can use advanced date and time formatting in any prompt or message that supports dynamic variables in the dashboard or API. We use [LiquidJS](https://liquidjs.com/) for formatting - see their docs for details.

Format a date or time using the LiquidJS `date` filter:

```liquid theme={null}
{"now" | date: "%A, %B %d, %Y, %I:%M %p", "America/Los_Angeles"}
```

Outputs: `Monday, January 01, 2024, 03:45 PM`

**Examples:**

* 24-hour time:
  ```liquid theme={null}
  {"now" | date: "%H:%M", "Europe/London"}
  ```
  → `17:30`
* Day of week:
  ```liquid theme={null}
  {"now" | date: "%A"}
  ```
  → `Tuesday`
* With customer number:
  ```liquid theme={null}
  Hello, your number is {customer.number} and the time is {"now" | date: "%I:%M %p", "America/New_York"}
  ```

**Common formats:**

| Format String | Output       | Description       |
| ------------- | ------------ | ----------------- |
| `%Y-%m-%d`    | 2024-01-01   | Year-Month-Day    |
| `%I:%M %p`    | 03:45 PM     | Hour:Minute AM/PM |
| `%H:%M`       | 15:45        | 24-hour time      |
| `%A`          | Monday       | Day of week       |
| `%b %d, %Y`   | Jan 01, 2024 | Abbrev. Month Day |

## Using dynamic variables in the dashboard

To use dynamic variables in the dashboard, include them in your prompts or messages using curly braces. For example:

```
Hello, {name}!
```

When you start a call, you must provide a value for each variable (like `name`) in the call configuration or via the API/SDK.

<Note>
  Always use curly braces (`{variableName}`) to reference dynamic variables in your prompts and messages.
</Note>