Heads up, folks, because it looks like T-Mobile will soon roll out a new fee for select customers upgrading to a new device. According to an image sent in by a tipster, T-Mobile will launch a $20 Assisted Service fee on July 31. The charge will apply to “the fraction of customers” that aren’t using JUMP!, JUMP! On Demand, or SCORE! and choose to upgrade their device in a retail store or through customer care. T-Mo explains … [read full article]