Prior to the advent of multichannel television sound broadcasting, the only way to transmit a stereo television show to homes was by simultaneous broadcasting on TV and radio stations. Proponents of non-receiver compatible ATV schemes suggest the same technique to achieve compatibility with existing NTSC TV sets: The non-compatible ATV signal will be transmitted on one channel and a second channel will carry a standards-converted NTSC signal. It is sometimes suggested that such simulcast techniques of ATV transmission are more efficient than augmentation techniques since, when the penetration of ATV sets into households reaches some limit, the NTSC simulcast channel can be eliminated, conserving bandwidth. In Britain, an almost identical situation occurred when 625 scanning-line television replaced 405. For many years, all programming was simulcast in both line rates with 405 eventually eliminated.