T-Mobile is EDGE in the US, because they counted on using a spectrum for 3G that the US govt keeps delaying for release (they won the auction for that spectrum a while ago). So, they're the slowest carrier, but they're also cheapest for a voice+unlimitedData plan. And they're very open about data plans, where other carriers aren't (AT&T will revoke an unlimited data plan if you use your unlimited rate too much; supposedly verizon will do the same).