Did some research on Software Defined Radios (SDR) which can receive radio waves. A tutorial by Crazy Danish Hacker shows that Cellular SMS messages are encrypted with the cell phones KS key, although the key is very short.
SDR’s can receive only but someone has created a linux driver to use a USB3 to VGA hardware dongle as a transmitter. can tansmit FM radio, GSM cellular, and fake GPS. https://hackernoon.com/osmo-fl2k-a-15-dtv-transmitter-fm-radio-hijack-and-gps-spoofing-device-68ac08ba7d76
I was interested as this could be used to fake locations for Pokemon Go but it could also be used in specific cases such as a cell phone that bypasses the lock screen when at home.