The FCC prohibited electronics makers from selling existing devices that operate in the 700MHz spectrum as of Friday in an order issued the same day. Any existing devices broadcasting in the 700MHz band will have to stop operating by June 12, the FCC said.

The main products affected by the ban will be wireless microphones, which have operated without FCC licenses in television spectrum for years. While many wireless microphones operate in lower spectrum bands, and will be able to continue there, the more than 300 models of wireless microphone and related components from 12 major manufacturers that will no longer be allowed to operate in the 700MHz band after June 12.

Among manufacturers listed on the FCC site with wireless microphones operating in the 700MHz band are Shure, Sennheiser, Sony and Samson Wireless. Representatives of Shure and two microphone groups didn't immediately respond to a request for comments on the FCC's order.

Most wireless microphone systems will continue to work because they don't operate in the 700MHz band, said Matthew Nodine, chief of staff in the FCC's wireless telecom bureau. Many wireless microphone makers and users have expected the FCC order since the agency auctioned off the 700MHz spectrum for mobile broadband and other uses in early 2008, he said.