In June 2010 the FCC instituted regulations that made it illegal to operate wireless microphones within the 700 MHz frequency range in the United States.
With the transition to digital television TV broadcasters vacated a large section of the UHF spectrum (from 698 to 806 MHz) so the FCC auctioned the 700 MHz band to the highest bidders (including AT&T and Qualcomm) to facilitate the development of wireless broadband Internet service throughout the United States. In addition, the FCC has reserved select frequencies in the 700 MHz band for emergency and national security purposes.
NOTE: The FCC is the Government agency tasked to regulate interstate communications by radio, television, wire, satellite, and cable in all 50 states, the District of Columbia and U.S. territories. The FCC sets the guidelines and regulations for all broadcast equipment (including wireless microphones).