Try this one:
$number = 'some-number';
$url = 'http://www.nokia.com/wal/care/warranty/?r=true&locale=en_IN&productId=&inst=&deviceId='.$number;
$post = curl_init();
curl_setopt($post, CURLOPT_URL, $url);
curl_setopt($post, CURLOPT_RETURNTRANSFER, 1);
$result = curl_exec($post);
curl_close($post);
print_r(json_decode($result));
It will output a json like below:
stdClass Object
(
[warrantyStatus] => N <-- this checks whether it has warranty or not!
[errorMessage] =>
[token] => 4551c7686...
[productCode] => xxxxx
[pp1] => N
[pp2] => N
[pp3] => Y
[pp4] => Y
[typeDesignator] => RM-xxx
[isValidIMEI] => Y
[imei] =>
)