How to screen instruments during the exam and how to send text messages on mobile phones?

At present, the school's mobile phone signal shields are all full-band, which can shield all 2G 3G 4G signals, 2.4G WIFI signals and Bluetooth signals of China Mobile, China Unicom and China Telecom. So as long as the screen is on, the mobile phone can't send text messages.

Secondly, the mobile phone screening machine screens the mobile phone cards installed in the mobile phone, regardless of the brand and model of the mobile phone. As long as the mobile phone uses mobile, Unicom and telecom, the following cards will be blocked.

There is a post saying that after the automatic selection column of mobile phone network operators is closed, the manual selection of networks will not be blocked. In fact, this is not correct, because the mobile phone screening machine screens all the mobile phone frequencies under the three operators, so no matter how it is switched, it will be blocked, which means that no matter what mobile phone card is in the shielding range of the screening machine.

This is inevitable for any number segment cracking or frequency band cracking, because no matter which number segment or frequency band you use, it is within its shielding range.

There is also Bluetooth software, because its frequency will also be blocked.

The only way is to install a cell phone signal amplifier near the place where cell phone signal shielding is used to compete with it. The stronger the cell phone signal, the harder it is to shield.