Curl, problém s poslaním dat do formu [POST]

<?php

$url = "http://www.poslatsms.cz/"; // From URL to get webpage 	contents.
$post_fields ='?action=Send&recipients=&operatorID=1&gateID=1&textsms=Ahoj&cislo-prijemce=123456789&cislo-odesilatele=&odeslat=Odesílá+se...'; 
$ch = curl_init(); // Initialize a CURL session.
curl_setopt($ch, CURLOPT_URL, $url); // Pass URL as parameter.
curl_setopt($ch, CURLOPT_POST, 1); // use this option to Post a form
curl_setopt($ch, CURLOPT_POSTFIELDS, $post_fields); // Pass form Fields.
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // Return Page contents.
$result = curl_exec($ch); // grab URL and pass it to the variable.
curl_close($ch); // close curl resource, and free up system resources.
echo $result; // Print page contents.
?>