I bought this when I switched from AT&T to T-mobile. TM's signal is much weaker and doesn't penetrate my apartment like ATT's does in downtown San Francisco.  The signal is OK pretty much everywhere else so I got this booster for home.  Does it work? Probably, if you are willing to drill a hole in your wall, run the cable to the roof, have a spare outlet and are willing to put up with the extra electricity charge and equipment necessary.  My landlord will not let me drill or install the cable.  I tried putting it in a couple of windows and it didn't improve the signal at all; apparently not high enough.