37 Installation and maintenance of telecommunications equipment; Installation and maintenance of computer hardware Installation and maintenance of surveillance systems; Installation and maintenance of sound systems; Installation of cellular boosting equipment; Installation of access control systems; Installation of network cabling and wiring; Installation of fiber optic cables; Repair of telecommunications equipment; Repair of computer hardware; Repair of surveillance systems; Repair of sound systems; Maintenance of telecommunications equipment; Maintenance of computer hardware; Maintenance of surveillance systems; Maintenance of sound systems