I live overseas and I always have issues receiving texts on my australian telstra phone (eg. mastercard 3d secure, nab (was locked out of internet banking for 9 months there until I landed back in aus), mygov and qantas). Even though the phone works perfectly while in australia, it does not receive texts in time outside of australia (i get quite a few verification texts either coming through an hour late or not at all).
My Qantas account was set up 20 years ago and I have no clue as to the verification questions (I have tried everything but only from overseas - I will try with a vpn as someone suggested above (I also could not book anything on jetstar from overseas (a month ago) and their chat does not come up, but these are other issues)).
In june/july I could no longer log into my qff account (the app still worked but I wanted to check reward seats). I messaged on facebook (who are really nice but could not help) and emailed them (who always take weeks to reply, if at all) about the problem. A few weeks later I noticed I had the option to verify with email which I used a few times. But then I returned to australia for christmas and this option seemingly disappeared... I am not sure if anyone else has been given the option to verify via email but this solved all my problems (until it disappeared again). I have emailed qff again (over a week ago) so i expect access to my account in a few weeks hopefully!
I am not sure if the email verification option was just temporary or if it was a trial etc. but I loved it and I really hope they change it permanently to that (that or generate a code in the qff app). All this extra security is too much, but if they need it for insurance etc. then at least they should make sure it works.