T-Mobile isn’t exactly the carrier of choice these days. After their failed merger with AT&T, they seem to be lost in carrier limbo. Verizon and AT&T have the largest 4G LTE coverage, Sprint has the only true unlimited data plans, and all three of them offer the iPhone. So where does that leave T-Mobile? T-Mobile knows it has to do something, and it appears that something, is unlimited data for $20 a month.