Sending post requests through curl using proxy. Feasible?

There is hosting, and it website. The site has a php script that uses curl — prehistory

So, there is a request for prohibited in Russia address. The query uses curl with proxy via:

curl_setopt($ch, CURLOPT_PROXY, 'xx.xx.xx.xx:xxxx');

But this method is not working. How to make it work?

Well, of course the hosting blocks access to the address. But can we ignore the moment?