While I'm sure that Fi and Google Voice are better than almost any other carrier based SMS security, this does nothing to convince me to ever use SMS 2FA.
"Your Fi number is tied to your Google Account." -- I'm sure you've seen cases of people's google accounts being randomly locked for no reason. Now you lose access to make a call too!
The last thing I'd ever trust security to is SMS. Lots of good technical details here:
I sort of disagree. With social engineering, it could be easier to reset someone's password with a SIM swap than traditional means. For many years, PayPal refused to do true 2FA and I cringed at having to choose between no 2FA or SMS-based. Phone numbers are much easier to source through public records than many people realize. As someone who has had the same primary cell phone number since I was a teenager, I’m honestly shocked it isn’t in more places (I’ve taken great pains to limit it getting out, but I’m still shocked). That scares me enough to almost get a second number, but that’s such a pain in the ass and not a great solution.
That's not really on the table though. We are not talking about your local tech illiterate bank here. We are talking about securing your Google account which is likely used to SSO authenticate with many other accounts.
