Types of Communications
The next area is the directional nature of your communications channel. Three basic forms of communications channels can be selected. They are:
One way (simplex)
This is a service that is one way and only one way. You can use it to either transmit or to receive. This is not a common channel for telephony (voice) because there are very rare occasions when we speak and everyone else only listens. Feedback is one of the capabilities we pride in our communications, which would be eliminated in a one-way conversation. Broadcast television is an example of simplex communications.
Two-way alternating (half duplex)
This is the normal channel we use in a conversation. We speak to a listener, then we listen while someone else speaks. The telephone conversations we engage in are normally half duplex. Although the line is capable of handling a transmission in each direction, the human brain can’t deal well with simultaneous transmit and receive.
Two-way simultaneous (duplex) or full duplex
This is used in data communications where a device can be sending to a computer and receiving from the computer at the same time. The direction of the information can be at differing speeds, such as 1200 bits/s toward the computer from the keyboard (humans cannot type much faster than that) and 9600 bits/s from the computer.
This introduction is meant to teach you about the functions and technology of a Central Office.
Analog to Digital Bandwidth
The Telephone Network
A Topology of Connection
Network Hierarchy (pre 1984)
Network Hierarchy (post 1984)
North American Numbering Plan
The Subscriber Extension
Local Access and Transport Areas
Wiring Connections: Hooking Things Up
Types of Communication
Lines Vs. Trunks
Foreign Exchange Signal