to mobile handsets. Currently, MSOs are engaged in disputes with content providers such as Viacom over rights to stream TV and movies to tablet computers over the MSO's cabling infrastructure. The State of the Industry Number of devices Each operator must determine the number of devices on which each user account is allowed to view content. If too many are authorized, will subscribers give their passwords to friends and relatives? Technological issues Operators need to make their content compatible with the operating systems and software of the many different mobile hand- sets that can be used to view video. Backhaul Services Another way that cable operators add services to their existing infrastructure is by leasing spare capacity on their backbone networks to mobile operators. MSOs use their backbone networks to link their local cable TV facilities to centralized headends that distribute TV and movies and perform functions such as billing and links to Internet and other networks. Backhaul services that mobile providers lease link cell sites (towers and antennas) to the data centers that support functions such as security and billing. Large cable TV operators as well as small mobile operators lease backhaul capacity in locations where they don't have their own backhaul infrastructure. See Chapter 7 for more information on backhaul and cell sites. Endeavors in Mobile Services Cable MSOs offer limited wireless services on Clearwire's and Sprint Nextel's mobile networks. Of Time Warner Cable's 12 million subscribers, only 13,000 subscribed to mobile broadband by the end of 2010. These services are offered on Clearwire's net- work and are for data only, not voice. Comcast also offers mobile services in certain of its cities on Clearwire's network. However, both Time Warner Cable and Comcast have announced plans to end their partnerships with Clearwire. Comcast along with Time Warner Cable and Bright House Networks have all invested in Clearwire. Due to Clearwire's continuing losses, Comcast and Time Warner Cable hav