Earlier quoted context omitted.
Yup lost my phone for a few months until my provider deleted my number and moved it on to some one else, now I am locked out of my paypal. I tried to find a pay as you go sim where the number doesn't expire and I would use that exclusively for 2FA but such a sim does not exist in the UK, most expire after 3 months the longest is 6 months. Now I know this is an issue but it doesn't seem like there is anything I can do…
You could avoid using SMS for 2FA. Most websites offer TOTP as first choice for 2FA. For the ones that insist on SMS 2FA being first choice, I don't bother using anymore. I delete the account and find another provider.
"most websites" has not been my experience at all. Sure, for the big ones like email that's and a lot of dev tooling that's the case. But there's a huge amount of services that requires SMS verification and once you loose access to that number you get locked out. A very common case is loosing ones phone (or having it stolen), at which point you have to log into your accounts again from another device but also don't have access to your SIM anymore.