Hi. My question is involving cell networks, carrier locking/ unlocking, and baseband firmwares. First of all, what makes a particular model of phone that is sold/ branded on a particular network different from its other variants? If I have a Galaxy S5 that is on T-Mobile, how is it different from the Galaxy S5 on AT&T? Aside from the differences of GSM and CDMA, what makes a T-Mobile phone, or an AT&T phone special in that it has its own radio firmware? Do each varriant of a device have a different baseband processor? Why do they have their own firmwares? What happens to the radio when you unlock a phone?