Allowing safe connection of users to Lync servers from smartphones, tablets, and any other external device, LyncShield prevents unauthorized devices (mobiles/desktops) from connecting to corporate network, avoids usage of Active Directory (AD) credentials, and protects against account lockout/DDoS. Features include Two Factor Authentication/device registration, MDM client-based Lync server access, Lync mobile smart card login, RSA token authentication, and Exchange Web Services protection.