gravityforms-validate phone NL

/**
 * NL mobile phone validation
 Landline: (((0)[1-9]{2}[0-9][-]?[1-9][0-9]{5})|((\\+31|0|0031)[1-9][0-9][-]?[1-9][0-9]{6}))$
 Mobile: (((\\+31|0|0031)6){1}[1-9]{1}[0-9]{7})$
 set css class phone field to: mobiel
 */
 
add_filter( 'gform_field_validation', 'validate_phone', 10, 4 );

function validate_phone( $result, $value, $form, $field ) {

    
    
    $pattern = '/^(((\\+31|0|0031)6){1}[1-9]{1}[0-9]{7})$/i';
    
    if ( $field->type == 'phone' && ! preg_match( $pattern, $value ) &&  !(strpos($field->cssClass, 'mobiel') === false) && $result['is_valid']  ) {        
        $result['is_valid'] = false;
        
       $result['message']  = empty( $field->errorMessage ) ? 'Dit is geen mobiel nummer.' : $field->errorMessage;
   }
   
    return $result;
}