Once upon a time, T-Mobile and the iPhone were friends. Even though AT&T had exclusive rights to the iPhone, T-Mobile was a significantly cheaper, friendlier, and less busy carrier that also used GSM. T-Mobile welcomed the owners of unlocked iPhones with open antennae. But that golden era is over, reader Brielle tells us. She’s been using iPhones on TMo for four years now, and is beginning to experience problems with her signal. It just so happens that her area has recently been upgraded for 4G service…right around the time her iPhone’s signal crapped out. They’re happy to sell her a new 4G Android phone, though.