the closest cell tower to me is on the other side of a hill.  when i stand on my roof i can get 1 bar of signal strength.  inside reception is zero.  i originally purchased&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/zBoost-YX-510-Cell-Phone-Signal-Booster-Dual-Band-Unit-for-Home-or-Office/dp/B000J2XZ1K/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">zBoost YX-510 Cell Phone Signal Booster Dual-Band Unit for Home or Office</a>, but had to return it because it did not work for my situation.  i then bought the older version of this unit (did not have gain adjustments) and it worked flawlessly for me, though the range was only about 20 feet.