This is a great travel idea thanks to my local Optus shop.

The challenge: How can I continue to have access to my phone account if I were to lose my handset while overseas? Because of 2-factor authentication, I need my phone account to access my online banking (as well as stuff stored on the cloud.)

The solution: Pack a spare blank SIM card in my luggage. If the lets-not-think-about-it-too-much were to happen, all I have to do is call Optus in Oz, and get the phone account switched across from the lost SIM to the spare SIM; then stick that spare SIM into a new handset.