alt Hacker News2FA over SMS is stupidly bad. It's worse than TOTP in every aspect including this reason. It is also much less secure. You could start switching accounts to TOTP regardless of this and then decide if you want to switch your number later when you have the option.
TOTP is portable and can be backed up.
I went a little bit off on a tangent, the stupidity of SMS 2FA is a pet peeve of mine.
If I lose my phone I have no totp access or sms access
I walk to the local phone shop and get a replacement sim for my number with a few of bits of ID and I regain sms access. Totp access is gone forever.
It’s clearly not worse that totp in every way.