But while John Shepard III was making plans to further expand the Yankee Network's FM properties, there was a major obstacle. The Yankee Network faced a powerful opponent—the Radio Corporation of America (RCA—ironically, majority owner of NBC), which saw FM as a threat to its established AM radio business. RCA was also concerned that Yankee's technique of "networking" their service around New England via inexpensive, off-air FM relays instead of AT&T phone lines, would open the door to many less well-funded groups establishing competition to RCA's established network, NBC. RCA, under general manager David Sarnoff, successfully pressured the Federal Communications Commission (FCC) to move the FM radio spectrum from 42–50 MHz to 88–108 MHz in 1945. This required massive hardware retooling at all FM broadcasters. Some affiliates dropped out, forcing the Yankee Network to lease phone lines from AT&T to fill in the holes between stations. The added costs to broadcasters and the obsolescence of all FM radios at the time set back FM broadcasting for a decade or more.