I gave M$ my mobile number for their MSN hotmail. It was the only was I was able to get my account back after it was hacked along with my WoW account back in January. They changed my password, but couldn't remove the mobile number from the profile. The password reset option was changed so that it wouldn't be set to my backup email account, but rather sent to the standard account. I managed to get the email on my phone, changed my password so I could log in on a computer, and then set it up to a stronger password a few minutes later. Account support was less than helpful because I no longer pay for my MSN account. They kept telling me, there's nothing we can do about it, because you aren't a premium member. My response was, "So I paid for your services for 10 years, and that means nothing to you?" (I used to get internet access through their narrowband package) Apparently not, but at least I had my mobile number on file so my email got sent to my mobile phone.