Why is the signal from the library so bad?

Recently, I often visit the school library because of the final exam, but whenever I approach the library or walk into the library, my cell phone signal is cut off, which makes me miss many calls. What is the reason?

Topsignaljammer  2022.

Recently, because a library has received many complaints, some citizens disregard other people's feelings and make loud calls in the library. No matter how prompt or persuasion it is useless, in order to ensure the quietness of the library, a library Spend tens of thousands of yuan to introduce phone jammer, which are installed in reading rooms with dense readership.

Citizens reacted differently to the installation of cell phone jammers in libraries.
Some areas in the library are shielded from mobile phone signals. Some people think that it is inconvenient to contact in an emergency, and some people say that they can finally have a quiet learning environment! What do you think about whether the library should use a cell phone jammer?