gistfile1.php[345]

<?php

$url = 'http://***.php';
$data = array(
    'channel' => '***',
    'message' => 'ほげらほげら',
    'password' => '***',
);
$options = array(
    'http' => array(
        'method' => 'POST',
        'content' => http_build_query($data),
    ),
);

echo file_get_contents($url, false, stream_context_create($options));