zBoost ZB575-A TRIO SOHO Tri Band AT&T 4G Cell Phone Signal Booster, up to 2,500 sq. ft. High Performance Tri-band Signal Booster-coverage Up To 2,500 Sq. Ft (up To 70 Db System Gain) Ideal For Homes & Buildings That Have Reliable Outside Connection Reduces Dropped & Missed Calls & Provides Faster 4g Data Performance For Multiple Simultaneous Users.Boosts performance On IPhone , Samsung , Android & Other Phones & Mobile Devices. Compatible With Mobile Phones & Devices Operating On Tat 4g Lte, Cell (800 MHz) & Pcs (1900 MHz) TROUBLESHOOTING:Please refer page 10 in the user manual attached below for troubleshooting instructions.