iOS OVH API Send SMS Error - php

Question

I'm trying to execute a PHP script inside my iOS app. It have later to send SMS automatically with the OVH SMS gateway, but for the moment, I only try to connect with my IDs to this service without sending anything.
I get an error 500 (server internal error), and I can't see where is the problem. Here is the tutorial I'm following (in french) : https://www.ovh.com/fr/g1639.envoyer_des_sms_avec_lapi_ovh_en_php
And this is my script (I verified secret keys and it seems to be good, but I don't understand what is the "POST" line commented at the top) :
<?php
/**
* # Instantiate. Visit https://eu.api.ovh.com/createToken/
* to get your credentials
* GET /sms/
* GET /sms/sms-XXXXXX-1/jobs/
* POST /sms/sms-XXXXXX-1/jobs/
*/
require __DIR__ . '/vendor/autoload.php';
use \Ovh\Api;
$applicationKey = "XXX";
$applicationSecret = "XXX";
$consumer_key = "XXX";
$endpoint = 'ovh-eu';
$conn = new Api($applicationKey,
$applicationSecret,
$endpoint,
$consumer_key);
$smsServices = $conn->get('/sms/');
foreach ($smsServices as $smsService) {
print_r($smsService);
echo '{"success":1,"error_message":"All clear"}';
}
?>
And finally my Swift request :
func sendSmsAutoRequest(completionHandler: (responseObject: NSDictionary?, error: NSError?) -> ()) {
let prefs = NSUserDefaults.standardUserDefaults()
let username = prefs.stringForKey("username")!
let messageText = prefs.stringForKey("messagetext")!
let parameters = ["contactsSms": contactsSms, "username": username, "messageText": messageText]
request(.POST, "http://XX.XX.XXX.XXX/dontworry/sendSms.php", parameters: parameters as? [String : AnyObject]).responseJSON { request, response, json, error in
completionHandler(responseObject: json as? NSDictionary, error: error) }
}