Spencer shifted from CEO to Chairman and CTO in early 2007 .
He is the founder , chairman and CTO of Digium , an open - source telecommunications supplier most notable for its development and sponsorship of Asterisk .
founder shifted from CEO to Chairman and CTO in early 2007 .
He is the founder , chairman and CTO of Digium , an open - source telecommunications supplier most notable for its development and sponsorship of Asterisk .