Microsoft has just acquired PhoneFactor, a competitor of Los Angeles-based, two-factor authentication provider TeleSign. Microsoft said it is buying PhoneFactor, which provides phone-based multi-factor authentication, and will be integrating that technology with key Microsoft technologies like Active Directory, Windows Azure Active Directory and Office 365. PhoneFactor provides similar services to TeleSign, using phone calls, texts, and other means of authenticating users, as a way of better securing logins into enterprise applications and other services. TeleSign, headed by Steve Jillings, has quietly grown into a major provider of those kinds of services to the top internet service providers; the company does not disclose its customers, but most users using two-factor phone authentication from major Internet services are doing so through white-labeled services from Telesign. Jillings sold one of his last companies, FrontBridge, to Microsoft back in 2005.