JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://igorescobar.github.io/jQuery-Mask-Plugin/js/jquery.mask.min.js"></script>
<section id="callback_header_js" class="form_holder clear form_holder_js">
    <form id="header_form" action="/include_areas/ajax_sms_form.php" method="GET" enctype="multipart/form-data">
        <input required="" class="itext input_mask_js" value="" name="BIG_NUMBER" />
        <button class="isubmit" type="submit">Перезвоните</button>
    </form>
</section>

JavaScript

$(".input_mask_js").mask("+7(999)9999999");
$('#callback_header_js').on('submit', function (e) {
    if ($(".input_mask_js").val()) {
        var m_method = $(this).attr('method');
        var m_data = $(this).serialize();
        $.ajax({
            type: m_method,
            url: '/include_areas/ajax_sms_form.php',
            data: m_data,
            success: function (result) {
                $('.form_holder_js').addClass('display_none');
                $('.text_result_js').addClass('display_block');
            }
        });
    }

    return false;
});