If your business uses Microsoft Exchange, odds are that you’ll need a Microsoft Exchange 2016 CAL. A CAL is a Client Access License. These additional licenses serve as a safety measure to prevent unauthorized access to servers, giving your business, school or organization an added layer of security. CALs are assigned to one person each and each person on your team will need one to use Exchange. My Choice Software offers CAL licenses for Microsoft Exchange standard and professional at affordable prices. CAL licenses are part of the Microsoft Volume Licensing Program.