With 2G the network verifies the handset and the handset blindly trusts the network. It's not technically a downgrade, A5/0 null cypher is a perfectly valid cho

With 2G the network verifies the handset and the handset blindly trusts the network. It's not technically a downgrade, A5/0 null cypher is a perfectly valid choice of the 4 available. Sure it screws you as a user but it's not going to cost the network so that's fine. Clarification: Notification to null encryption still exists, and iirc then it's actually mandatory. It's just that you can disable the warning by setting a bit on the simcard which it seems nearly every operator in the world does. As it was so unused the majority of even vaguely modern phones don't seem to have bothered writing the code to handle it anyway. iirc, India _only_ uses A5/0 as it's illegal for them to use crypto [someone please clarify and educate me].