大华乐橙监控设备如何开发？

下载了乐橙开发者中心的web端的SDK，然后注册了开发者中心，现在获取accessToken第一步失败了。

 function http_post_json($url, $jsonStr){
    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $jsonStr);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
            'Content-Type: application/json; charset=utf-8',
            'Content-Length: ' . strlen($jsonStr)
        )
    );

    $response = curl_exec($ch);
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    return array($httpCode, $response);
}

$url = "https://openapi.lechange.cn:443/accessToken";
$jsonStr = json_encode(array('phone' => '18600000000'));
echo $jsonStr;
list($returnCode, $returnContent) = http_post_json($url, $jsonStr);
var_dump($returnCode);
var_dump($returnContent);

有具体的报错信息吗？