, swheaties wrote

giving MS my phone number is required to set up an account.  ... And now they want to be able to spam me on the single device that I reserve for communicating with my friends and family.

The phone number is subject to Azure's privacy policy: http://www.windowsazure.com/en-us/support/legal/privacy-statement/?l=en-us.

Microsoft doesn't sell your phone number on to third parties, and doesn't use your phone number commercially.

The reason they ask for it is because they need to turn over the information to the FBI in the case where you set up a fake hotmail account, pay for the Azure account through a stolen credit card and then use the Azure account through TOR to set up illegal websites such as exploit websites. So the legal advice to the Azure team was to require a second physical medium that they can pass over to law enforcement in the event that the website is conducting illegal activity.