Audio (voice) and video signals at one time were mainly analog signal. The telephone system is an example of a system that used analog signals where voice sound waves get transmitted from one caller to the next using electromagnetic signals to transmit the sound waves. To transmit the audio signal, a certain amount of bandwidth is needed for the transmission to go from one caller to the next over the telephone system. When the sound waves come into the handset, the sound transducer converts the sound waves into the analog signal. Analog video signals work in the same way, but a camera is used to create the picture and more bandwidth is needed to isolate video signals in order to transmit the signal from the television station to viewer’s television.
Advancement in technology has given us digital signals which refers to electromagnetic pulses being transmitted, and those pulses are two different binary codes that are represented by 1 and 0. These binary codes are used to transmit data, which can be in the form of video, and voice analog signals. The analog signals are converted using sampling and quantization.
Private branch exchange (PBX) is a telephone switch that an organization owns or leases to give the location the switch is at access to the public telephone system. PBX allows the user at the location to dial a three or four digit number, also known as an extension, to reach another co-worker at the same location. To dial out to a different location, the user will press “8 or 9” and then the rest of the number used to reach the location. Voice over IP (VoIP) is used to deliver multimedia and voice communications over an internet protocol (IP) network, just like the internet.