[kintamanimatt]

Then use a different provider.

I'm not trying to suggest you get a redundant SIM on the same account; that's not possible. You get a second prepaid account (with a different number) with either the same or a different carrier.

[herbst]

How would that solve the initial issue tho? I still would have to change my phone number with dozens of different services.

[kintamanimatt]

If you're looking for a work-free backup/restore solution, those don't exist. The point is that you'll at least have immediate access to an active number from your home country that you can give to your banks or whatever. This means your banks (and others) aren't going to be weirded out by that non-domestic phone number, which is a problem you were describing.

Sometimes you'll be able to port your number too.