sports and other niche programming). Cable and satellite providers pay the networks a certain rate per subscriber (the highest charge being for ESPN, in which cable and satellite providers pay a rate of more than $5.00 per subscriber to ESPN). The providers also handle the sale of advertising inserted at the local level during national programming, in which case the broadcaster and the cable/satellite provider may share revenue. Networks that maintain a home shopping or infomercial format may instead pay the station or cable/satellite provider, in a brokered carriage deal. This is especially common with low-power television stations, and in recent years, even more so for stations that used this revenue stream to finance their conversion to digital broadcasts, which in turn provides them with several additional channels to transmit different programming sources. History Television broadcasting in the United States was heavily influenced by radio. Early individual experimental radio stations in the United States began limited operations in the 1910s. In November 1920, Westinghouse signed on "the world's first commercially licensed radio station", KDKA in Pittsburgh, Pennsylvania. Other companies built early radio stations in Detroit, Boston, New York City and other areas. Radio stations received permission to transmit through broadcast licenses obtained through the Federal Radio Commission (FRC), a government entity that was created in 1926 to regulate the radio industry. With some exceptions, radio stations east of the Mississippi River received official call signs beginning with the letter "W"; those west of the Mississippi were assigned calls beginning with a "K". The number of programs that these early stations aired was often limited, in part due to the expense of program creation. The idea of a network system which would distribute programming to many stations simultaneously, saving each station the expense of creating all of their own programs and expanding the total coverage beyond the limits of a single broadcast signal, was devised. NBC set up the first permanent coast-to-coast radio network in the United States by 1928, using dedicated telephone line technology. The network physically linked individual radio stations, nearly all of which were independently owned and operated, in a vast chain, NBC's audio signal thus transmitted from station to station to listeners across the United States. Other companies, including CBS and the Mutual Broadcasting System, soon followed suit, each network signed hundreds of individual stations on as affiliates: stations which agreed to broadcast programs from one of