I don't give my phone number to anybody who doesn't need it. Lots of places ask/demand it, but it's always actually optional. There's no law that says you have to have a phone, after all.
So, there's no way I'm going to give up my phone number in exchange for a log-in on a free web-site.
So, there's no way I'm going to give up my phone number in exchange for a log-in on a free web-site.