What is "phonefactor"

PhoneFactor is a multi-factor authentication system which utilizes phone calls to verify identity. With multiple out-of-band methods (phone call, text message, and push) and an OAUTH passcode option, PhoneFactor provides flexibility for users and a single multi-factor platform for IT to manage.

On October 4, 2012, it was announced that Microsoft had acquired PhoneFactor. The PhoneFactor service is now available as Windows Azure Multi-Factor Authentication. In addition to securing on-premises applications and identities, the service now also works with cloud applications like Office 365 that use Windows Azure Active Directory.