You just need to insert a sim card and sd card into this bad boy and leave it at a location you want to monitor.
You can call the device and listen live, you can send a text msg to this device to start an audio recording, video recording, or even take pictures. It also has an auto call back feature, this means when it detects sound in the room it can call your phone.
You can hide it as you please, whether you place it on another object or use mount tape to put it under a table or similar, the limit is your imagination.
Battery duration depends on usage. Stand by it will last few days or even weeks. Audio recording few days sometimes hours. Video recording consumes the most power thus may only get 2 plus hours of video. If you are a technician you can connect a direct power supply to it removing the battery limitation. Again it’s up to your imagination