tail carriers have no incentive to provide competitive roaming rates to competitors in the nationwide carrier's territories. Roaming refers to subscribers using their cell phones beyond their own carrier's coverage areas. Competition for roaming can be problematic for data services because they require large amounts of capacity, which might not be available on an incumbent's network if it is near capacity. Clearwire is an example of a wholesale provider. Clearwire, which is 48 percent owned by Sprint, has some retail customers but is now concentrating on wholesale customers. Time Warner Cable and Comcast, which sold mobile services on Clear- wire's network, have announced plans to discontinue these sales. Clearwire has not completed building out its nationwide network. It has nationwide spectrum. Clearwire owns the largest amount of spectrum of any carrier in the United States. Carriers that operate primarily as wholesalers save money on marketing, retail stores, billing, and staff. It hopes to make up for lower per-user revenues with savings in operating costs and its customers' quantity leases. Depending on the arrangement with each carrier customer, it might also offer handsets and billing platforms to the carrier. The FCC has repurposed satellite spectrum for terrestrial service to alleviate spec- trum shortages. Terrestrial cellular refers to service delivered via towers, as opposed to wireless service transmitted through satellites. It is likely that a satellite provider will request permission to use a portion of this spectrum for terrestrial service. Competition, Industry Structures, and Regulations Cream Skimming: Concentrating on Profitable Markets When carriers enter a new market, they often do SO in areas where there is potential for large profits. This concept is known as cream skimming. Cream is skimmed from lucrative markets such as wealthy suburbs or markets with few providers. This occurred when AT&T and Verizon first offered cable TV service bundled with voice and Internet access. They often sel