### [How to Provide Additional Phone Field Validation](https://wpforms.com/developers/how-to-provide-additional-phone-field-validation/)

**Published:** February 2, 2021
**Author:** Editorial Team

**Excerpt:** This tutorial will show you how to provide additional phone field validation such as preventing toll-free numbers from being entered in your form. 

**Content:**

Would you like to provide additional phone field validation? For example, if you’d like to prevent users from entering toll-free numbers in your **Phone** field, you can easily achieve this with a small PHP snippet. In this tutorial, we’ll walk you through the steps on how to prevent toll-free numbers from being entered in your form.

## Creating the form

To begin, you’ll need to create your form and add your **Phone** field to your form as well as any additional fields you’ll need on your form.

If you need any help in creating your form, [please see this documentation](https://wpforms.com/docs/creating-first-form/ "How to Create Your First Form").

![to provide additional phone field validation you will first need to create your form.](https://wpforms.com/wp-content/uploads/2021/02/wpforms-additional-phone-validation.jpg)

## Setting the Phone field format

For the purpose of this documentation, we’re going to prevent any phone number starting with `8` or `+8`. Depending on which **Format** you’re using for the **Phone** form field will depend on the code snippet you’ll need to use below.

![Select the format you want to use on your phone field](https://wpforms.com/wp-content/uploads/2021/02/wpforms-additional-phone-field-validation.jpg)

## Additional Phone Field Validation

Now it’s time to add the PHP snippet you’ll need. There are two different snippets and this depends on what **Format** was set for the **Phone** field when you created your form.

If you need any help in adding snippets to your site, [please see this tutorial](https://wpforms.com/developers/how-to-add-custom-php-or-javascript-for-wpforms/ "How to Add Custom PHP or JavaScript for WPForms").

#### US Phone Format

```

/**
 * Custom US format phone field Validation on submit (reject defined prefixes).
 *
 * @link  https://wpforms.com/developers/how-to-provide-additional-phone-field-validation/
 */

function wpf_dev_process_validate_phone($field_id, $field_submit, $form_data)
{
        //  Only check for US phone field format
	if ( 'us' === $form_data[ 'fields' ][$field_id][ 'format' ]) { 

		$stripped_phone = str_replace(array( '(', ')'), '', (string) $field_submit);

		$prefixes = [ '8', '+8' ];

		$regexp = implode( '|', $prefixes);

		if (preg_match( '/^[' . $regexp . ']/', $stripped_phone)) {
			wpforms()->process->errors[$form_data[ 'id' ]][$field_id] = esc_html__( 'The number should not start with "' . implode( '", "', $prefixes ) . '"', 'plugin-domain' );
		}
	}
}

add_action( 'wpforms_process_validate_phone', 'wpf_dev_process_validate_phone', 10, 3);
```

#### Smart and International Phone Format

```

/**
 * Custom Smartphone and International field Validation on submit (reject defined prefixes).
 *
 * @link  https://wpforms.com/developers/how-to-provide-additional-phone-field-validation/
 */

function wpf_dev_process_validate_phone( $field_id, $field_submit, $form_data ) {

   $prefixes = [ '8', '+8' ];

   $regexp = implode( '|', $prefixes );

   if ( preg_match( '/^[' . $regexp . ']/', (string) $field_submit ) ) {
      wpforms()->process->errors[ $form_data[ 'id' ] ][ $field_id ] = esc_html__( 'The number should not start with "' . implode( '", "', $prefixes) . '"', 'plugin-domain' );
   }
}

add_action( 'wpforms_process_validate_phone', 'wpf_dev_process_validate_phone', 10, 3 );
```

Both of these snippets will look at the **Phone** field value when the form is submitted and if it begins with the number **8** or **+8** the form will not submit and an error message will appear.

![By providing an additional phone field validation you can easily prevent toll-free numbers from being entered on your form.](https://wpforms.com/wp-content/uploads/2020/06/wpforms-additional-phone-validation.jpg)

And that’s it! You’ve successfully added additional validation for your **Phone** form field. Would you also like to prevent certain emails from being entered as well? Check out our tutorial on [How to Restrict Email Domains](https://wpforms.com/developers/how-to-restrict-email-domains/ "How to Restrict Email Domains").

## Reference Filter

[wpforms\_process\_validate\_phone](https://wpforms.com/developers/wpforms_process_validate_phone/ "Using the wpforms_process_validate_phone filter")

**Categories:** Fields

**Tags:** PHP

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