<?php
$PostURL="https://test.com/test.php";
$XMLReq="<data><OrderId>102</OrderId><tracking_number>123456</tracking_number></data>";
$username = "test";
$password = "test";

$curl = curl_init($PostURL);
curl_setopt($curl, CURLOPT_USERPWD, $username . ":" . $password);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, $XMLReq);
curl_setopt($curl, CURLOPT_RETURNTRANSFER ,1);
$str1 = curl_exec($curl);
$info = curl_getinfo($curl);
curl_close($curl);

print_r($str1);
?>