Why VoIP is headed for your cell phone?

For millions of users, voice over Internet protocol, or VoIP, is lowering phone bills for calls they make from their PC or land-line phone. But soon VoIP could cut cell-phone bills, too - most of all for international users.

It's a hard concept to get your head around: Many customers already pay a flat monthly fee for a bucket of calling minutes within U.S. But for business travelers, international students and immigrants, calling abroad can add up quickly. However, if they're already paying for a data plan, routing international calls over their phone's data connection -- using VoIP -- instead of a carrier's voice network, they can save considerable money. 

That's the bet that Mino Wireless is making. The Sunnyvale, Calif.-based startup is offering cut-rate VoIP calls at 2.2 cents a minute to 40 countries, and claims to be the first to introduce VoIP on mobile phones to the U.S. market. To use Mino, you need service from Cingular, Nextel or T-Mobile, a data plan, and an up-to-date phone that can run Java.