public static function get_user_contacts_parameters() {
        return new external_function_parameters(
            array(
                'userid' => new external_value(PARAM_INT, 'The id of the user who we retrieving the contacts for'),
                'limitfrom' => new external_value(PARAM_INT, 'Limit from', VALUE_DEFAULT, 0),
                'limitnum' => new external_value(PARAM_INT, 'Limit number', VALUE_DEFAULT, 0)
            )
        );
    }