Access Control & Security Management Systems | CEM Systems CEM Systems is a leading provider of access control & fully integrated security management systems, installed worldwide where security is paramount. Going beyond access control , CEM has a dedicated team that integrates the AC2000 access control and security management system with external systems such as video, fire and intrusion products. CEM Approved Reseller Network CEM has a network of Approved Resellers around the world that install and service CEM access control systems .