The error, which occurs during the checkout process, is...
Rating and Service 1.0001 0 An unknown error occured while attempting to contact the UPS gateway : Rating and Service 1.0001 0 An unknown error occured while attempting to contact the UPS gateway
If you prefer to use ups as your shipping method, please contact [the site I'm working on] via Email.
This is an easy fix and on some hosting platforms such as ours which has increased security will cause this. Locate the includes>modules>shipping>upsxml.php
Uncomment line number 655 //curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
Save the file and all should work.