Apple and Google Are Introducing New Ways to Defeat Cell Site Simulators, But Is it Enough?
www.eff.org
Cell-site simulators (CSS)—also known as IMSI Catchers and Stingrays—are a tool that law enforcement and governments use to track the location of phones, intercept or disrupt communications, spy on foreign governments, or even install malware. Cell-site simulators are also used by criminals to send...

I’m not sure if this is strictly privacy or more security related but it does affect iOS and Android and could have privacy implications. It was enough to make me to turn off 2G anyway.