[cloudwalking]

Because everybody I know has my real phone number.

[WesleyJohnson]

If that is indeed the only thing stopping you from using it, you can port your existing number to Google Voice.

http://googlevoiceblog.blogspot.com/2011/01/port-your-existi...

[TextyTeam]

Our view is that many people don't want to break out of their existing contracts with their carrier -- which one has to do when porting their current # to GV

[billyg2]

Many people are stuck in long term contracts with their carriers. When you port your #, it breaks that contract.

This is definitely not for everyone, but if you look at the comments from users, you'll see why people are using it:

https://chrome.google.com/webstore/detail/dkfhfaphfkopdgpbfk...