How to stop church members from using cell phones at church?

The church is a sacred place, and the priest reminded parishioners to turn off their phones before the service began, but some still did not follow. How to prevent this?

Topsignaljammer  2022.3

In churches in Western countries, as well as some religious churches in China, the church is a sacred place, and any uncivilized behavior should be prohibited, and the ringing of the bell will disrupt the behavior of others for a week, which is not civilization. Therefore, many churches maintain a quiet atmosphere and install cell phone jammers to block the signal if necessary. You can imagine rude and ignorant answering the phone loudly. As a result, cell phone jammer are a great solution to keeping quiet in church.