> Also, Microsoft will require a phone number once you try to log into an Outlook email account from other IP address than you have signed up with.

That's quite a good idea.. They're effectively using your IP as a 2nd factor auth for those people who refuse to use 2 factor. If, like many people, you have a static IP at home, and they whitelist IP's your sessions roam to, you may never need to log in from a new IP.