This week, T-Mobile and Sprint officially asked the Federal Communications Commission for approval to merge. If the merger goes through, there will only be three big wireless providers to choose from. And with net neutrality out the window, people are worried that cell phone service will keep getting more expensive. But there is another collection of wireless providers like FreedomPop, Mint, Boost Mobile, Tello and Metro PCS that offer an alternative, at least on price. These companies are what's called mobile virtual network operators. They've traditionally been known as prepaid providers who rent wireless service from the big telecoms and resell it to consumers. There are more limits on the plans, and you sometimes can't use the latest and greatest phones on all of them, but they're starting to offer more options and ramp up their marketing. Roger Cheng covers wireless carriers for CNET. He spoke with Marketplace Tech host Molly Wood about how MVNOs work. (06/20/2018)