[BuildTheRobots]

Actually with 2G (especially A5/0, /1, /2), it's very much the algorithm that's the problem.

A5/2 which is the precursor to the encryption used for 3G and LTE is a lot better but there's still issues that are only just coming to light.

[chisleu]

I'm referring to modern networks. 2G is deprecated and going bye bye very soon.

For 3G/4G/LTE, the issue is the home cell sites host the keys and people exploited those devices to create the DIY stingrays.