This phone signal booster will only work in US, won't work in other countries</b><p>The Cell Phone Signal Booster could work for most of U.S. and Canadian carriers on 850MHz band 5 including AT&T and more (not compatible with Nextel)<p>Operation Frequency: Band 5<br>Frequency Range:Uplink:824-849MHz;Downlink: 869-894MHz<br> Max.Gain(dB):62dB<br>I/O Port:N-female on both ends<br>Power Supply:Input AC100~240V 50/60Hz, Output DC 12V 2A<p>These things are absolutely critical for the cell phone signal booster to work:<p>1. Make sure your cell signal is GSM/CDMA 850MHz Band 5 frequency,or the cell phone signal booster couldn't work for your cell phone.<p>2. The cell phone signal booster could only make the weak signal stronger,it couldn't generate any signal. So make sure the Outdoor Yagi Antenna towards the cell signal tower,and could receive receive 2-3 bars of stable signal,or the cell phone signal booster couldn't work very well.<p>3. It is better to determine the exact in different location until the highest signal strength is received on your phone(most amount of bars).Once you ascertain the best location then permanently mount the outdoor yagi antenna. Keep the distance between the outdoor yagi antenna and indoor whip antenna should be above 32ft and make sure a proper amount of physical separation between them.