Telecommunication systems allow for the exchange of information over distance through various forms of communication like audio, visual, and combined signals. The basic elements of any communication system include a transmitter that sends information through a communication medium to a receiver. Communication systems can be classified in different ways such as wired vs wireless, narrowband vs wideband, and the transmission mode like simplex, half duplex, or full duplex. Modern communication methods include landline phones, wireless networks, cable TV, radio, and cellular networks with a long history of developments in both wired and wireless technologies.