In October 1999, Rosenberg left Lucent to serve as the chief technology officer of dynamicsoft.
At dynamicsoft, Rosenberg conceived of, drove requirements for, designed, and lead software development for industry's first SIP application server.
He also acted as architect and first product manager for dynamicsoft presence engine, conceived of, helped developed requirements for, and designed SIP firewall control proxy and co-developed the architecture for the dynamicsoft network application engine.
[8] In 2013, Rosenberg left Skype to return to his alma mater Cisco Systems, taking the position of CTO and Vice President of Cloud Collaboration.
[9] In January 2019, he followed his former Cisco Systems boss Rowan Trollope to Five9, joining the company as CTO and Head of A.I.