Best Overall Product

Zer01 Mobile

How does $69.95 per month for unlimited voice and data sound—without a contract? That's the appeal of Zer01, which uses highly efficient VoIP technology to let users make phone calls over existing cellular networks. This new breed of carrier will sell a variety of Windows Mobile devices starting on July 1 that can tap into its service, but it will also enable users to bring their unlocked BlackBerrys, Android phones, and other handsets. An extra $10 per month will allow subscribers to add international calling to 4 destinations. Zer01 Mobile promises that it will take as little as 5 minutes for the company to update your phone's SIM card to make it compatible with its network.