How Do Cell Phone Boosters Really Work?
A Cell Phone Booster is a passive device designed to reflect stray radiation in the body of the phone, and re-radiate that signal to improve the phone’s performance.
Internal Cell Phone Boosters fit digital, analog and tri-band phones. Cell Phone Boosters will enhance a signal, even weak ones. But it will not help when there is no signal at all…
Here is some interesting info on these items: 50 Cell Phone Boosters.