bill customers and provide customer service for repair and billing issues. TracFone Wireless, Inc., a unit of Mexico's TelMex, is an MVNO. It supplies prepaid service under a number of brand names but owns no mobile network infra- structure. Other MVNOs have been successful tapping into particular ethnic groups. For example, China Telecom announced plans to start an MVNO targeting Chinese residents such as students, tourists, and business people who travel between China and the United States. It plans to offer handsets that can operate in both countries. AT&T, Verizon, and Sprint offer wholesale services to MVNOs. Wholesale ser- vices are a way for network owners to recoup some of their investments associated with upgrading networks. Sprint sells unused capacity to MVNOs. It is able to "fill up more of its pipes" and earn revenue, even though revenue per user for wholesale services is lower than that for retail customers. The State of the Industry Carriers also arrange for connectivity to their network to be embedded in devices. For example, e-readers, USB modems (also referred to as dongles), and laptop com- puters can have cellular connections embedded directly in them. This is a way for developers of new applications to gain access to mobile networks. Selling Wholesale Services Exclusively All major mobile operators offer wholesale services to other carriers, but some opera- tors provide wholesale services as their primary or only strategy. The availability of wholesale networks has important implications for competition and innovation. Orga- nizations that develop innovative mobile services on handsets are able to offer them on wholesale carriers' networks, thus precluding the need to build their own. This is important because mobile network operators that sell directly to customers might be reluctant to provide their finite network capacity for competing offerings. Another advantage of wholesale networks is that these operators can offer com- petitive roaming rates to carriers without nationwide coverage. Re