Layers of the International Organization for Standardization

Telecommunication System Options

NTC/360

June 21, 2010

Phillip Coleman

Telecommunication System Options

The telecommunications industry has come along way from the first days after the invention of the telephone. Many new updates and tools have been added to make telecommunications a much easier process. The developments in telecommunications functionality has provided several options for how the service can be setup and used. This paper will discuss the differences between four different options. The comparisons will be with rotary and dual tone multi-frequency, wide area telecommunications and leased lines, private branch exchange and Centrex and lastly the layers of the International Organization for Standardization-Open Systems Interconnection (ISO-OSI) model.

Rotary and Dual Tone

The main difference in rotary and dual tone multi-frequency (DTMF) is primarily the method in which a phone call is made. The old rotary phones had a wheel also known as a dial on the phone with small holes with a number inside them. In order to make a phone call the individual would place his or her finger in the hole with the corresponding number and spin the wheel around as far as it would go before releasing it; this process would continue until the entire number was dialed. The phone would then create and interruption in the electric current in the phone wires. The number of interruptions sent was based on the number dialed; therefore if a three was dialed three interruptions would be sent as the wheel turned back to the starting position.

Dual tone multi-frequency phones then came along and once again made things much easier. DTMF is also known as touch tone which simply means the corresponding number that was pushed on the phone sends two tones at the same time to the phone company. The phone company knows the number being dialed by the sound of the tone and in turn pushes the call through.

WATS and Leased Lines

Wide area...