The blocks of the 800 band that cells phones use(d) are blocked, you can't tune them in for privacy issues, however, the 400 band is wide open, hence the invention of the frequency doubler The doubler allows you to listen to the complete 800 band without restrictions. It's a little device that runs on a 9v battery and plugs inline with the antenna, turn it on and it doubles the frequency you are tuned into.