I'm using a 1st gen iphone with the $20 unlimited data. ATT wants to charge me $35/month if I upgrade to 4. Trying to save money but don't know if this would work. I can pick up the iphone 4 unlocked from Asia. How can I keep my existing plan on iphone 4? Any ideas? Will this fly? Tell AT&T I lost my iphone, mail me a new 3G SIM? I read people are cutting their cards to fit it in iphone4. Thanks for any advice.