Automatic adjust the system gain to avoid the repeater self-excitation.  
Automatic dormancy when no user make the calling
If frequency doesn't match, it can't works.
the signal booster coverage depends on the outside signal strength received by the outdoor antenna.
the coverage gets wider if signal strength is strong.
If your area don't have this frequency, the device can't work.

Frequence range downlink:	2110-2170mhz	Brand:	ATNJ
Frequence range uplink:	1920-1980mhz	Model:	as-YW
Gain:	70dBi	MPN:	Does Not Apply
Output power:	23dBm	Connectivity:	Wired/Phone Antenna Port
Warranty:	3Years	Compatible Brand:	Universal, for Amazon, for Apple, for ASUS, for BlackBerry, for Blackphone, for Casio, for CUBOT
Indoor antenna:	Penal antenna	Bundle Listing:	Yes
Cable length:	Indoor 5m + outdoor 20m	Remote Antenna:	Yagi antenna
Network:	3G	Country/Region of Manufacture:	China