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CSU
Channel Service Unit. A device to terminate a digital channel on a customer's premise.
D
DB25
The standard 2pin connector used for RS-232 serial data communications.
DB9
The standard 9-pin RS-232 serial port on most computers
Dedicated Subscriber Lines
Communication lines (usually twisted pair) that are used to connect on-premise telephone equipment (such as a
PBX/KSU) to the Central Office. Also referred to as direct lines.
Default PBXgateway
Normally the IP address of a router. Used to specify where IP packets are to be sent that are not destined for the
same network number.
Dial Line
A telephone line which is part of the Public Switched Telephone Network and is accessed through an automatic
dial-up function.
DNS
Domain Naming System. A mechanism used in the internet for translating names of host computers into
addresses.
Example: DNS would change a computer name such as mck.com to the actual numeric IP address of
xxx.xxx.xxx.xxx.
Domain Name
The fully qualified name of a domain of a network. Example "mck.com".
DRAM
Dynamic Random Access Memory. A readable/writable memory chip used to store data.
DS-0
Digital Service, Level 0. It is 64,000 bps, the worldwide standard speed for digitizing one voice conversation using
PCM.
DSP
Digital Signal Processor. A specialized computer chip designed to perform speedy and complex operations on
digitized signals.
E
Ethernet
A local area network used for connecting computers, printers, workstations, terminals, servers, etc. Ethernet
operates over twisted wire and over coaxial cable at speeds up to 100Mbps.
PBXgateway II System Administrator's Guide
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