Ajax POST请求无效

I want to get BlackBerry PIN on this page: http://m.tokobagus.com/iklan/drees-import-51336153.html/?&opt=2&int=1&pg=1&catid=230&subcatid=230

It sends an Ajax POST request to this URL: http://m.tokobagus.com/search/ajaxbb

their script is:

$.post(url,{pin:$("#advscrw").val()},function(k){k=$.parseJSON(k)});

success result: {"status":1,"data":"xxxxxxx"}

pin is the only parameter, and its value is N0Q2MzY2MUQ=. But when testing the request using PHP, the results is {"status":0,"data":null}

    $options = array(
    'http' => array(
        'header'  => "Content-type: application/x-www-form-urlencoded
",
        'method'  => 'POST',
        'content' => http_build_query($data),
    ),
);
$context  = stream_context_create($options);
$result = file_get_contents($url, false, $context);

var_dump($result);

What's wrong?

It only responds with the actual data if it sees the X-Requested-With: XMLHttpRequest request header.

'header'  => "Content-type: application/x-www-form-urlencoded
" .
             "X-Requested-With: XMLHttpRequest
",