Telecommunications Network Technology
The telecommunications industry transmits voice and electronic data through wired and wireless networks.
Wired, or "wireline," telecommunications networks connect homes and businesses via wires, or "land lines," to central hubs. Switching equipment at the hubs routes incoming transmissions to their destinations. Wired networks are used to transmit cable programming and broadband Internet service as well as phone calls.
Wireless networks use radio towers to transmit cellular phone calls and Internet service. Cell phone towers convert radio transmissions received from individual phones to land-line or microwave data streams for transmission through the public switched telephone network and then, if necessary, convert the data stream back to a radio signal for transmission to the receiving cell phone or computer.
All of these facilities require substantial electrical power. That power is usually drawn from the electrical grid and rectified to DC, typically at -48 volts for wired networks and +24 volts for wireless networks. Because, however, the electrical grid is subject to disruption and the telecommunications network supports services that people rely on heavily, adequate effective backup power is essential.