Digium, Inc.
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Appendix D: Glossary and Acronyms
CO
central office
The CO houses local switching equipment. All local access lines in a
particular geographic area terminate at this facility (which is usually
owned and operated by an ILEC).
CPE
customer premises equipment
Terminal equipment which is connected to the telecommunications
network and which resides within the home or office of the customer. This
includes telephones, modems, terminals, routers, and television set-top
boxes.
DS0
Digital Signal, Level 0
A voice grade channel of 64 Kbps. The worldwide standard speed for
digitizing voice conversation using PCM (Pulse Code Modulation).
DS1
Digital Signal, Level 1
1.544 Mbps in North America (T1) and Japan (J1) -up to 24 voice
channels (DS0s), 2.048 Mbps in Europe (E1) - up to 32 voice channels
(DS0s). DS1/T1/E1 lines are part of the PSTN.
DS3
Digital Signal, Level 3
T3 in North America and Japan, E3 in Europe. Up to 672 voice channels
(DS0s). DS3/T3/E3 lines are not part of the PSTN
DTMF
Dual Tone Multi-Frequency
Push-button or touch tone dialing.
