In 2008 I moved to Japan from The Netherlands for a year as a graduate student. I didn't want to bother with my Dutch phone number there, so I looked for alternatives. My bank uses one time codes that are normally sent to you via SMS when you perform a transaction. These can also be pregenerated and sent to you via mail. The online banking environment simply asks me to enter code number
x.
I never changed back, so now I receive a new sheet of numbered codes whenever I've used a certain number of them. Nowadays I scan this sheet of codes, run an OCR task, and import the codes in my password manager¹. So when the bank asks for code 519:
pass -c bank/ing/tan/519
And I have the code on my clipboard.
I wonder how long ING (my bank) will allow this method to exist… The alternative used by Dutch banks is a small token generating device they provide to all customers (I think only ING mentioned above doesn't do this yet). This requires no phone number either, just the (tiny) physical device.
I wonder what happens if I tell my bank that I no longer have a phone number I can be reached at?
1: https://www.passwordstore.org/