PhoneFactor

PhoneFactor is a proprietary multi-factor authentication owned by Microsoft. It uses telephone calls, SMS messages, and push notifications to verify identity.^[1][2]

PhoneFactor was originally developed by Positive Networks Inc., founded in 2001 by Tim Sutton and Steve Dispensa.^[3] The PhoneFactor product was launched in 2007,^[4] and the company changed their name to PhoneFactor Inc. in 2009.^[3][5] On October 4, 2012, Microsoft acquired PhoneFactor,^[6] and the PhoneFactor service is now available as Azure Multi-Factor Authentication. In addition to securing on-premises applications and identities, the service now also works with cloud applications like Microsoft 365 that use Windows Microsoft Azure Active Directory.