<?php

$post = [
  'list'      => 23,
  'name'      => 'Subscriber John',
  'email'     => 'john@subscriber.aa',
  'activated' => 1
];

$ch = curl_init('http://hirlevel.sandros.eu/a/subscribe?key=f953d4b526fdffda0d58bcd39fbbab29800f31ec8c6bcff53af359cd6528337e5bda05f3faf3f2beef4fb1cc8eeee906be67d6bc7c4b04af61dfc239d6b079e1');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, $post);

// execute!
$response = curl_exec($ch);

// close the connection
curl_close($ch);

// lets see
var_dump($response);