sorry, but most likely no. If it’s for 2-factor authentication, phone/SMS-based ones have also been shown to be less secure as well as they are susceptible to SIM-jacking attempts.

Mastodon already has built-in app-based 2FA support, and I’m already using it for my account. There’s no need to use mobile phones for this.

How would I "know" this?

I see these claims on websites all the time "we'll never XYZ your ABC". How are they verified?

I'd have to be convinced it's useful or does something. On the surface,, it sounds like security theater.

I'm not sure how it's actually useful or prevents misbehavior. It seems like it only works by being a hindrance. Doing that intentionally is a bit ableist, to a greater extent than it's effective.

... because you **cannot know** your # won't be saved and sold and spammed.

@profcarroll

I have a disposable SIM I use when I have to give it a phone number, so I'm already in a weird category. That said, I can be persuaded to use that number for registration if I have to.

But I'd honestly be reluctant to trust any site that said this, because:
+ if it's genuinely not stored, a spammer can use the same number for 10,000 registrations and then just get another number, or
+ some process will complain about the number being reused, showing it really is being stored somewhere.

@pixelfed

Besides the privacy issue, there is standing in solidarity with those who do not have mobile phones.

What makes you think that everyone on the planet even HAS a mobile phone? In many parts of the world those cost money and not everyone has them. And even people who do have them to often don't want to give out their number to random services on the Internet, for fear of getting increased junk/spam calls or other misuse. There is really know way of "knowing" your number wouldn't be stored and misused, as your question presupposes.

Personally I think this is a terrible idea, both because of the discrimination against people who do not have mobile phones, but also because you are asking users to trust random instance owners not to do anything bad with their phone numbers. The "bad apples" among instance owners (can you absolutely guarantee there aren't any?) are probably hoping something like this will be enabled real soon now!

this only fights spam accounts on large centralized instances.

And we don't want large, centralized instances.

We want to encourage many, small, federated instances. So IMO any effort to improve spam fighting, should go to tools and tech for fighting spam in a world with many, small, federated instances.