Human beings have used different methods long-distance communications of which the telegraph and the telephone were important. The telegraph was instrumental in the colonisation of the American West. During the early and mid-twentieth century, the American Telegraph and Telephone Company (AT&T) enjoyed a monopoly over U.S.A.’s telephone industry. In fact, the telephone became a critical factor in the urbanisation of America. Firms centralised their functioning at city headquarters and located their branch offices in smaller towns. Even today, the telephone is the most commonly used mode. In developing countries, the use of cell phones, made possible by satellites, is important for rural connectivity. 

In context of communication system what does OFC mean ?

Optical Fiber Cable

In context of communication system OFC stands for 'Optical Fiber Cable' which is a major breakthrough in the development of communication as these allow w large quantities of data to be transmitted rapidly, securely, and are virtually error-free.