cURL Error No : 7 - Couldn't connect to host!

I did ask a similar question around last week and did got some info on how to proceed with curl call errors.

My scenario - I am doing a cURL call to a webservice, and I would say around 90% of times the curl calls are successful for the same calls, but it fails for many! I did some googling which said , the server might be blocking my calls!

My Question

• How I would be certain that my calls are blocked? (Note : the webservice servers are internal to the company, so I might get a help from开发者_开发问答 administrator)
• Is there any way that i can debug on my end!? or would need help from administrator!?
• How should I resolve it to make sure 100% calls are successful
• And just in case its a windows server (not sure which version) for the webservices