If you are using mobile broadbands on dongles, you will discover that the IP is always changing. Uploading to sites or downloading from file storage sites is impossible. This is because the IP changes with each refresh and if the download is not completed within a fixed time frame, it gets cut off.
There are also times when users who are disturbed by the fact that some censored sites are not allowed by your ISP. You can change your IP address by using programs out there. I have tried a few like Tor: anonymity online, notmyip. But I have found one very good one called ultrasurf.
This program allows you to use 3 pre-defined IP addresses from the US. It is lightweight and no installation required. Simply execute it off and it will start your windows Internet Explorer browser. Those who are firefox fans will be slightly disappointed. But the Tor browser uses firefox. I do not like Tor browser is because it takes a long time to get connected. It also does not work if your time is set wrongly.
Antivirus see such programs as malware and the resident protection goes all out to stop it. So you may need to go into the settings of your antivirus to disable the resident feature before starting this application.
Going through this program, you can upload and download anything with no issues. It is very reliable. Best of all this program is totally freeware.