Social Media GM’s social media chief joins Porter Novelli-owned PR shop After four years with the automaker, Christopher Barger moves to Voce Communications, which was recently acquired by Porter Novelli. By Michael SebastianMarch 24, 2011 SHARE He will be the company’s senior VP for global programs. Porter Novelli acquired Voce Communications in February. To read the full story, log in. Become a Ragan Insider member to read this article and all other archived content. Sign up today Already a member? Log in here. Learn more about Ragan Insider.