I am a loyal customer of T-Mobile, despite the few dropped calls and rare low service areas, I have no complaints. But lately, the iPhone has caught my attention. I thought I had to change providers to get this phone, and heard a lot of negative comments about both AT&T and Verizon. Recently a co-worker explained to me that iPhones can be unlocked (whatever that means) and I can keep T-Mobile and get the iPhone too. Before committing, I want to know what disadvantages would I experience in doing this? What if I did change providers and go to Verizon? What could I expect? Will I still be able to use the iPhone's features with each provider?