Community Dial Office
Encyclopedia
A "Community Dial Office" (CDO) was a small Class 5
telephone exchange
in a rural area. CDOs could be step by step
, all relay or crossbar
. They provided capacity for 1000 or fewer customers. Late in the 20th century they were replaced by remote concentrator
s connected to the host office, which may be several miles away.
Class 5 telephone switches
A Class 5 telephone switch is a telephone switch or telephone exchange in the Public Switched Telephone Network located at the local telephone company's central office, directly serving subscribers. Class 5 switch services include basic dial-tone, calling features, and additional digital and data...
telephone exchange
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
in a rural area. CDOs could be step by step
Strowger switch
The Strowger switch, also known as Step-by-Step or SXS, is an early electromechanical telephone switching system invented by Almon Brown Strowger...
, all relay or crossbar
Crossbar switch
In electronics, a crossbar switch is a switch connecting multiple inputs to multiple outputs in a matrix manner....
. They provided capacity for 1000 or fewer customers. Late in the 20th century they were replaced by remote concentrator
Remote concentrator
In modern telephony a remote concentrator, Remote Concentrator Unit , or Remote Line Concentrator is the lowest level in the telephone switch hierarchy.Subscribers' analogue telephone/PSTN lines are terminated on concentrators...
s connected to the host office, which may be several miles away.