From Geek.com:
The mobile networks in the US are designed to prevent new competition from entering the market. The US isn’t likely to see a new carrier to deliver a service that functions the same way that the current traditional carriers do. In order to succeed, a radical concept needs to be deployed. Republic Wireless hopes to deliver that radical concept, by offering unlimited everything for $20/month. The catch? The service is designed for you to use Voice over IP and your local wireless network whenever you can.