On October 4th Microsoft announced the acquisition of Phonefactor, a provider of phone-based multifactor authentication. Microsoft informed us about this acquisition only in a blog post on their Windows Azure blog at the MSDN (Microsoft Developer Network) website . There is no official press release out, but Phonefactor itself provides some information at their website . Obviously Microsoft didn’t consider this as being a major acquisition but just another piece of technology which adds to their major strategic initiatives, including Windows Azure. However it could turn out as an acquisition which massively affects the market for multifactor authentication.