CoTap, a provider of mobile communication services for the workplace, has raised $5.5 million in Series A funding led by Charles River Ventures, with participation from Emergence Capital Partners. The San Francisco-based company aims to provide a secure and unified way for employees to communicate in the workplace. CoTap will use the capital to scale its engineering team. In conjunction with the investment, Charles River’s George Zachary and Emergence Capital’s Jason Green will join the company’s Board.