IT IS A LISTENING DEVICE.
YOU CAN PICK UP PHONE CALLS IN IT FROM OTHER PEOPLE.
Just saw a streamer take franklin to trevor, get out, switch players, and then took the car as trevor (maybe it matters who drives, since no one else has heard it yet)
I just listen to black girls fighing on the phone, and other little blips of sound.
It needs to point at stuff, then you will hear things.
His phone was out whenever it happened, but may not be required.
The "guns" are antennas! Point them at sh*t!
Discuss findings here because other topic is too broad, this is SpaceDocker ONLY.