Features :

1-  The world's   infinite distance voice transmission ( using the GSM signal transmission, no distance limit can be inter-provincial cross-border) ;

2-  dual microphone design, ultra-clear sound  ;

3-  Small size as a match box , portable ;

4.-  900/1800/1900 frequency

5-  With lithium battery inside too .

6-  Function of SMS to control voice activated on or off.  If you don't want to voice activated function in some times , you can remote control to disactivate it . It can save power .

7-  Voice activated function. If the surrounding voice is up to 60db, the monitor will automatically dial back to your phone  to remind you that there is poeple arround the monitor and they are talking , you can choose to listen or call back to monitor.

Usage:

1.  Take out the monitor device ; 
2.  Insert a SIM sim card into the card slot ;
3.  Press power button to turn on ;
4.  Wait for several seconds ;
5.  Use your mobile phone or other telephone to call on the number in monitor  ; Or you can activate voice activated fuction ,then to wait for calls from the monitor  ;
6.  You achieve to listen or monitor the surrounding of the monitor . 
7.  charging methods: use USB transfer cable to connect to the device, the other end connected to the charger