Comms could be disrupted if the local authorities had wanted to kill the cell towers in the area. Cops and military don’t use cell phones. You get cell signal and blue tooth squelchers up and running and these folks can’t talk to each other. Their tactics require the use of instant communications. Squelch those and they would be stuck with UNIDEN type handheld walky talky type CB 40 channel(with sidebands) radios that might go several miles but can be jammed or listened in on. Lots more interference as well. There are some transceiver sets on the market that reach out farther but still are useless with the types of tactics these folks are using
If you make it so signals can’t go in and out, these protests would be easily scattered and rendered disorganized.
In many of the pictures, it appears they have other comm than cell phones.
Some of it might be sophisticated frequency hopping and encrypted.
...these fake cell towers tricks phones into connecting to it and can then obtain the phone's location and track the phone's location. In older, 2G networks, cellphones were required to verify themselves, or prove that the person using the cellphone had a valid service plan. But towers did not have to verify themselves. So, any device that sent out similar signals to the cellphone tower could "impersonate" that specific tower.Though more-advanced cellphone networks, such as 3G and 4G, have patched that security bug, the makers of these spying devices still tout their ability to track people's phones, which means there are still security bugs in the cellular network being exploited. The devices work by forcing phones to drop down to a lower, less secure 2G network.
...the devices can be small and incredibly inconspicuous. Some are set up in the backs of trucks that have a few antennas on them, but some are the size of a cellphone or are embedded in a vest.
The Russians have simulators that can track people from a mile away.
Source: LiveScience, 'Stingray' Spy Devices Are Eavesdropping in Washington, D.C.: Here's How. (I don't know how accurate this April 2018 article is)