Google: Signal Booster SCAM:
the sticker does nothing, its a scam, its literally just a sticker. the only signal boosters that you will see that work are external ..
The antenna booster stickers showed no measurable improvement in signal strength .... stating they work, it's my belief antenna booster stickers are a scam. ...
The only way to boost (or improve) the effectiveness of the antenna of a mobile phone is to take the signal from the output of the phone and fit an antenna that is larger and extends over the edge of the phone.
This way the antenna is "more effective" than an antenna that is close to the framework of the phone and has a better change of radiating the signal.
That's why antenna's in old-style mobile phones extended beyond the framework of the phone.
To expect the signal to "jump onto" a sticker then radiate more effectively that the original signal - is an improbability.