Installation and maintenance of PABX systems: Avaya, Panasonic, Grandstream, and Ericsson. CCTV camera installation: both IP and analog camera installations (Hikvision and Dahua). Intercom systems: analog and IP. Networking: TP-Link repeaters, D-Link switches, access points, and routers. Cabinets: 4U and 6U. Biometric systems: installation and programming.