 to use bandwidth efficiently. Providers are additionally adding capacity to last-mile, edge networks by laying fiber in neighborhoods closer to homes or by connecting fiber directly to individual homes. A central office is a centrally located building in which telephone company and cable TV providers locate their switching, battery backup, and transmission equipment. Transmission equipment is in the form of blocks where cabling is connected to, for example, DSL and Ethernet services. Technicians in remote network operating centers (NOCs) monitor signals sent over cabling connected to subscribers and central offices. Because of the need for sustainability during natural disasters, buildings that house central offices don't have windows and are built to withstand flooding, tornadoes, and hurricanes. Digital Subscriber Line Access Multiplexers Digital Subscriber Line (DSL) is a service that sends data over the same twisted pair cabling used for voice. DSL is gradually being replaced by fiber to premises, but is still used by residential subscribers and small businesses that don't have fiber. Telephone companies that have not invested in fiber to the premises (FTTP) offer DSL service for Internet access and other data services. It is also used where customers don't have access to cable modem service. (See below for a description of cable TV networks.) www.TechnicalPDF.com Using Small DSLAMs and Mini-RAMs for Internet Access with Digital Subscriber Line Service DSL Access Multiplexers (DSLAMs) aggregate traffic from multiple customers' DSL modems and translate electrical signals on copper cabling to light signals before sending traffic to the central office. From the central office Internet Service Providers (ISPs) transmit subscribers' traffic to the Internet or data networks over fiber-optic cabling. DSLAMs are located in a carrier's central office or in remote terminals, which are cabinets placed between the central office and the subscriber. The connection between the DSLAM and an ISP is a potential site for netw