A cell phone signal booster does improve cell phone reception by bypassing any interfering obstructions in the signal and amplifying a poor outside signal. However, a phone booster cannot fix the strength of a signal if the cell phone has no signal at all.
A cell phone signal booster works by an antenna attached to the roof of the home that sends a signal through a cable into an amplifier inside, where it is then sent to an antenna inside that broadcasts superior reception. The booster also functions in reverse, increasing the signal from the phone to the tower, establishing stronger two-way communication.
Influential factors on a cell phone's signal are distance from the closest cell tower and any obstructions that cause interference, such as mountainous terrain, concrete and metallic building materials. Dropped calls and poor reception result from a weak signal.