Jonathan Rosenberg, general manager of product strategy and research at Microsoft, has left Skype and returned to Cisco where he had worked in 2009. Rosenberg is widely known as the “father of session initial protocol (SIP)” according to a blog post from Andy Abramson.
Rosenberg was one of the guiding lights behind Facebook Messenger’s video calling service, having developed many aspects of the service from the ground up, including the deal itself and the launch. He also helped roll out the Windows 8 version of Skype.
This marks the third departure of a Skype executive since December, following former global head of communications Brian O’Shaghnessy in December and former Skype senior manager Edmund Read. These departures are occurring as Microsoft continues to integrate and streamline their products and services. The company is planning a sunset of Windows Live Messenger on April 8th as well as a linking of Skype to its Lync enterprise communications suite.