You can build an IMSI-catcher-catcher out of an Orbic RC400L cellular hotspot and the Rayhunter software published by the EFF.

https://www.eff.org/deeplinks/2025/03/meet-rayhunter-new-ope...

https://efforg.github.io/rayhunter/orbic.html

Literally just airplane mode. It's ended up being a rather excellent privacy toggle that operating systems have to implement well.

GrapheneOS has "2G Network Protection" which prevents your phone from connecting to 2G networks and it also can notify you if your cellular identifiers were accessed.

https://www.cape.co seemed suspicious to me but apparently they actually do manage to make decent security improvements on the cellular stack. They also donate 100k/year to GrapheneOS [1] which is cool.

https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

Yes there absolutely are!

The EFF has the Rayhunter project at https://github.com/EFForg/rayhunter - it is basically an IMSI catcher catcher. You install it on a pocket router and it detects typical signatures that IMSI catchers use, for example telling your mobile to downgrade from LTE to 2G making it easy for them to tell your device to join THEIR network and read the IMSI / IMEI for your device and possibly route your traffic through their network.

The device with Rayhunter installed will notify you when these signatures are being detected and you get a pcap file that you can dissect using Wireshark.

There are other tools that you can install on Android devices but Rayhunter certainly is a good start if you want to detect the use of IMSI catchers.

One caveat: IMSI-catching is a cat-and-mouse game, so no promises can be made that the Rayhunter heuristics catch all attacks.

faraday pouch.