This is a solution to solve poor cell phone signal. If you have a good signal outdoor but poor signal indoors, then this is exactly what you need. 

This product contains a cell phone signal repeater, two antennas and coaxial cable. 

The working principle is that the antenna receives signal from the base station and transmits it to the repeater, which will boost the received signal several times and then transmit it to the other antenna, and the antenna will broadcasts a good signal in the room. 

No more dropped calls and enjoy blazing faster data by one-time purchase. Suitable for apartment, basement, office, garage, etc.

Here's how to view frequency bands with your phone
iphone
1.Turn off Wifi
2.Key in *3001#12345#*
3.Press call
4.Tap: menu
5.Tap:Serving Cell Info
6. Scroll down to freq_band_ind

Android
Install an app Network Cell Info Lite on the Google Play store. It provides detailed network cellular information

*Make sure to check the frequency where you need to boost signal. 
*Before checking the frequency, kindly turn off the WiFi.
*While checking, stand in a place with a good outdoor signal.
*Try standing in different positions and checking multiple times to avoid any inaccurate results due to unstable signals.