[rsync]

"this method will only work with GSM network because ..."

Yes, that's true - but remember that all of our 3G/4G phones are also 2G phones and that if you disable/jam/overpower the 3G/4G signals the phone will very happily revert down to 2G, possibly with no encryption, and possibly in a way that you have to be very careful to even notice.

There are quite a few attacks that are mitigated by 3G/4G in theory, but in practice you're still vulnerable to because your phone can be downgraded to 2G by an outside actor.

[girvo]

Interestingly, the 2G networks are being (or have? I can't remember which) shut down entirely here in Australia.

[user5994461]

It works on all generations: 2G 3G 3.5G 4G LTE.