日本と海外をつなぐクラウドソーシング

The mobile phone is almost everywhere,but it brings us convenience at the same time, but also bring us many troubles. After all, not all mobile phone users know when to stop talking. At this time we need to use the cell phone jammer, to protect a quiet environment. For example, in churches, libraries and other places.
https://www.perfectjammer.com/all-cell-phone-jammers-blockers.html