For the week 2 individual assignment we have been asked to generate a paper describing the telecommunications system used in our work environment and provide definitions concerning the following terms – Rotary and dual tone multi-frequency, wide area telecommunications service and leased lines, private branch exchange and Centrex and finally the layers of the ISO-OSI model.
I have chosen to discuss the terms early in the paper, as I won’t be able to provide much detail concerning my firm’s telecommunication system due to confidentiality agreements. The later information will be high level as not to provide any detail that could be deemed a breach in compliance.
Rotary and Dual Tone Multi-frequency (DTMF)
Rotary and Dual Tone Multi-frequency (DTMF) refers to technology used at the handset to dial the number desired. While those born in the early 80’s may not have been exposed rotary phones, they were the only option available prior to the mass adoption of touchtone handsets. Rotary phones are identified by a wheel on the face of the handsets with finger holes. Each finger hole corresponds to a number. When the user wants to make a call they use their finger to spin the wheel from the point of the number they desire to a stop point, and release the wheel. This action causes the phone to first open the circuit, and then send a series of pulses that are keyed as the wheel returns to its start position. These pulses which are translated at the central office (CO) into their corresponding numbers are then directed to the desired destination.
As the technology progressed the rotary dial phone was replaced by touch tone phones. Faster then their predecessor, “typically 10 times faster” (Dean 2003, p. 197), these handsets utilized buttons associated with numbers that the user pressed. Touch tone phones use a technology called dual-tone multi-frequency (DTMF) to make a call. DTMF uses 2 tone frequencies to identify the number being...