Have you seen anyone talking loudly on the phone in public? Have you ever thought about how to reduce or even avoid this situation? The first thing you have to consider is related law enforcement, but it will not work. You might consider buying a GSM jammer, which is a jamming device designed specifically for GSM signals. Current GSM blockers not only interfere with GSM, but also block GPS and WiFi signals.
Here are the questions and answers about GSM jammers prepared for you. I hope to get your approval.