JQuery - JSONp communication with C# Web Service

HTML

<input type="text" id="txtNumber"></input>
<input type="submit" id="btnSentValue" value="Push Value"></input>

JavaScript

$(document).ready(function () {
    $('#btnSentValue').on('click', function () {
        var inVal = $.trim($('#txtNumber').val());

        if (inVal == '') {
            alert('The input is not a Number!');
            return false;
        }
        if (isNaN(inVal)) {
            alert('The input is not a Number!');
        } else {
            $.ajax({
                crossDomain: true,
                contentType: "application/json; charset=utf-8",
                url: "https://www.evicore.com/webservices/evicoreservice.asmx/HelloWorld",
                data: {
                    inNumber: inVal
                },
                dataType: "jsonp",
                success: function (data) {
                   alert(data);
                },
                error: function (jqXHR, textStatus) {
                    alert(JSON.stringify(jqXHR));
                }
            });
        }
    });
});