Why would curl ignore CURLOPT_TIMEOUT_MS (but honor CURLOPT_TIMEOUT)?

Question

I am using curl to call a web service API. The service can unresponsive so I want to set a timeout. When I use CURLOPT_TIMEOUT things work as expected. But when I use CURLOP

Answer 1

To close this question:

The version of curl I am using (7.15.5) doesn't support CURLOPT_TIMEOUT_MS. According to Greg I need at least 7.16.2.