There is nothing to be trusted about cell phone networks in 2018. The only two tools the public can use are signal.org and wire.com for secure communication, and they require a data connection. It will take at least a year from now for your cell phone provider to fix this issue, so that you know if you're connected to them, or your nephew's PAL receiver. This info is years old, so it's unlikely to get fixed any time soon. Enjoy the radiation beside your genitals as your cell phone spends its time trying to find something to connect to and share its information with, at least there's a comfortable warmth.
As you walk around with your cell phone on, you walk by different cell phone towers, which allow you to make a phone call no matter where you are. Your cell phone is always beaconing out; hey; which tower is closer?
Whomever responds first, wins.
Sometimes it's an IMSI catcher, a hacker, or a government agent, or sometimes it's a tower owned by your phone company that responds to your cell phone that it's clear for you to make a call -- but they're all motivated to make sure your cell phone stays with you, and that the GPS stays on, and your unique phone identifies you (MAC address, Bluetooth (LTE), IMSI number, and the same phone number) as that information is worth a lot. They've all turned off encryption, it's virtually non-existent for cell phone networks. This allows them to do man-in-the-middle (MITM) attacks where they just listen in the middle and allow your phone call to carry on. It can be recorded and shared, forever.
Which tower is your cell phone connected to right now? Is that even a legit cell phone tower you're connected to right now, or your neighbors briefcase? Who owns that device your cell phone is connected to?