function getAjaxObject() {
    var xmlHttp;
    try { xmlHttp = new XMLHttpRequest(); }
    catch(e) {
        try { xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); }
        catch(e) {
            try { xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); }
            catch(e) { alert("Your browser does not support AJAX!"); return false; }
        }
    }
    return xmlHttp;
}

function getActionUrl(action_name, params) {
    var url = '/index.php?action=' + action_name + '&';
    for (var word in params) {
        url += word + '=' + params[word] + '&';
    }
    return url;
}

function isAjaxSuccess(ajax) { if (ajax.readyState == 4) return true; return false; }

function processSMS() {
    var ajax = getAjaxObject();

    ajax.onreadystatechange = function() {
        if (isAjaxSuccess(ajax)) {
            alert(ajax.responseText);
        }
    }

    var params = new Array();
    params['phoneNumber'] = document.getElementById('phoneNumber').value;
    ajax.open("GET", getActionUrl('process_sms_form', params));
    ajax.send(null);
}