Fun fact. I once bought a very cheap Optus phone just to use for work 2FA (might have been PingID). Never registered it but it could still authenticate via the

Fun fact. I once bought a very cheap Optus phone just to use for work 2FA (might have been PingID). Never registered it but it could still authenticate via the Optus cell network using a lower level transport protocol. Meant I could use 2FA with no wifi connection and the phone in airplane mode to conserve battery.