Use short answers to explain the difference between:
o Rotary and Dual Tone Multi-frequency (DTMF)
o Wide Area Telecommunications Service (WATS) and leased lines
o Private Branch eXchange (PBX) and Centrex
o The layers of the International Organization for Standardization-Open Systems Interconnection (ISO-OSI) model
Rotary signaling is a way of dialing with the use of electric pulses corresponding to the number being dialed. It is used on the older versions of telephone units. DTMF is a way of dialing with the use of different frequency tones corresponding to a number being dialed. It is now widely used in the modern telephone units.
WATS is a telecommunication service that provides outgoing calls, incoming calls, or both to a subscribing customer. This service allows communication between stations at ...
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