When you take the streets to demonstrate your beliefs, it’s important to know your rights, but it’s also important to take steps to secure your phone from theft, loss, and, of course, surveillance.
The options for crowd surveillance are numerous. Stingrays and other IMSI catchers are controversial devices that have been used by local and federal law enforcement. These devices can trick your cell phone into connecting with it, instead of a cell tower, and intercept information (like SMS messages) without you necessarily realizing it. They can also extract identifying information from your phone and track your movements.
Even without fancy devices, law enforcement may be able to obtain information on your movements and activities from your wireless provider.