Touch America, Inc.

I have no idea how this company got my phone number but they call and call and call all day every day. they never leave a message, just call and hang up when voice mail answers. this has been going on for about 6 months and even though I answered once and told them not to call bak again, they continue calling. it is very annoying as I have no idea who they are or what they want. I have a prepaid cell phone so I cant put a block on this phone number. I had to get online and use a reverse directory to even find out what company it is.