$xml = '<?xml version="1.0" encoding="iso-8859-1"?><update><status>1</status></update>';
mb_detect_order('ISO-8859-1');
$xml = mb_convert_encoding($xml, "iso-8859-1");

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/xml; charset=ISO-8859-1;'));
curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 300);
$data =curl_exec($ch);

$dataPOST = trim(file_get_contents('php://input'));

$xml=simplexml_load_string($dataPOST) or die("Error: Cannot create object");
$enc=mb_detect_encoding($xml);

echo json_encode(array('status'=>$xml, 'encoding'=>$enc));