I purchased this to boost the signal for my T-Mobile based Samsung Galaxy S II. See my separate review of the phone. I have been a customer of Verizon for several years and reside in a chronic dead zone. Verizon cured the problem with a boosted signal, but when I decided to go with T-Mobile I inherited the same problem.  What is weird is that if I go a block away in the tower direction I get a very clear signal, so....?