"Un-carrier" T-Mobile is launching a new trade-in program for Apple's (AAPL -0.35%) iPhone. Prospective switchers can bring in previous-generation models to offset the upfront cost of a new iPhone 5 on T-Mobile, requiring $0 down. Sprint Nextel's (S) prepaid brand, Virgin Mobile, recently launched an aggressive switching campaign of its own, offering a $100 credit. However, AT&T (T 1.02%) and Verizon (VZ 1.17%) still have significant network advantages with LTE coverage, which is a key selling feature of the iPhone 5.

In the video below, Fool contributor Evan Niu, CFA, lays it all out for investors.