They don't have to. There are 2 "little ones" they can buy from (and often do without telling folks. Lots of Straight Talk / Net10 / TracFone devices buy from

They don't have to. There are 2 "little ones" they can buy from (and often do without telling folks. Lots of Straight Talk / Net10 / TracFone devices buy from Sprint or T-Mobile without explicitly telling you) While these smaller carriers aren't always a great replacement (in a lot of areas, for a lot of reasons) they provide enough competition to work well most of the time. For instance, both AT&T and Verizon now offer $60/month prepaid plans for smartphones with LTE data. That didn't exist a year ago. If AT&T had been able to kill T-Mobile, it probably never would have happened.