The so-called "cell phone jammer bag" is a kind of bag for storing mobile phones, except that the fabric has been specially treated (nano shielding coating, which can effectively block electromagnetic signals), so that it can block the signal connection between the mobile phone and the communication base station. When someone dials a mobile phone that has been put in the "mobile phone shielding bag", what they hear is a prompt such as "The user you dialed is temporarily unavailable".
Therefore, from the point of view of the principle of use, the "mobile phone shielding bag" is exactly the same as the practice of removing the battery in the power-on state circulated in the "private" (because the battery is removed in the power-on state, the mobile phone will be lost before it sends a shutdown message to the base station. Because of the power supply, the system will think that the mobile phone is not in the service area), which prevents the mobile phone from contacting the base station, but it uses more technical means to achieve it.
What needs to remind you is that please do not put the phone in the shielding bag for a long time, otherwise the caller will hear the prompt "The user you are dialing is turned off". Because if there is no signal for a period of time, The system will determine that the owner has shut down.