this my first post but i hope it help,
NET10 had just came up with there unlimited plan of $50 (talk,text and date (3G)) or $65 with all that + international calling to almost 50 countries, and they are saying on the SIM card kit, to bring your GSM unlocked or compatible phone , Iphone, Android, Smart phone.
and it should work, pop the sim in and follow the instructions.
I'm actually thinking seriously to switch to them after buying a AT&T HTC Vivid, thinking i'll be able to use with t-mobile 4G, to find the LTE Curse is on my Vivid.
i talked to a dealer of NET10 and he told me the NET10 uses both networks, and you are guaranteed to get 3G speed on any phone capable of having 3G speed.
this text is copied from NET10sim web page
"Use virtually any compatible or unlocked GSM phone with our NET10 SIM to get service on the best nationwide networks."
i got the sim, but it was 2 days after I paid for my t-mo for this month, I'll post my experience once I try it on my LTE cursed Vivid phone, and check the 3G service.
Hope this helped. :fingers-crossed: