The sticker is nothing. Mail me $20 and I'll send a magical boost to your phone. They're both as likely to work.

There is actually antennae to be purchased that can improve you signal. They plug into your phone though so it's not so wireless anymore. They can be purchased at truck stops.

Not sure if this helps, but I have a few customers in my area that placed car antennas on a window at their home and they just plug their phone into that at home. The actual antenna would mount on outside of a window and the cable would be on the inside(cable is about 4 ft). They swear it helped a ton. It doesn't boost you signal power, but it moves your antenna to the outside of the house, they said it gets them two bars on the antenna and they only get one bar or no bars without it. the signal would probably be about the same as you going outside to use your phone. This is actually a cheap fix as well, you can get those for as little as 30 bucks. So if you can get a good connection right outside your house this might be something to try.