When buying a smartphone jammer, should you pay attention to whether it is used indoors or outdoors?

It depends on whether the mobile phone signal jammer is to shield the inside of the room or the outside of the room. If you want to shield the inside of the room, you must put the jammer in the current room. It is best to place it a little higher, about 2 meters from the ground. Stand upright on the wall.
It should be noted that the jammer should not be placed directly in a place that is too hot, such as a place near a heater or a place near an air conditioner. This source of heat can interfere with the use of test signal jammers. Because, during use, the mobile phone signal jammer itself will generate some heat, if it is placed in a place where heat is generated, it will cause problems with the signal jammer. If you want to shield the outside, you have to choose an outdoor high-power shield, fix the device on the outside wall, and then point the antenna in the direction you want to shield.