A data transmission format comprised of 12 frames of 192 bits
each. A single 193rd bit is used for link control and error checking.
As an industry standard, D4, also known as SF, has been superseded by
the Extended Super Frame (ESF) format. However because ESF is not
backward compatible and there continues to be a large installed base of
channel banks and DS-1 Multiplexers that are based upon D4, it is still
the default private line formatting technique.
D-4 Channel Bank
A multiplexer used to convert 24 voice grade analog or data
channels into a DS-1. The D-4 is not equipped for
software- controlled provisioning or remote circuit testing.
A digital switching facility interconnection device. A DACS
allows reconfiguration of lower levels of capacity within a circuit
without the need for manual changes in the interconnections. A
DACS is similar to a Mux, but a DACS
permits software changes which would require physical changes with
a MUX.
An inactive fiber-optic strand without electronics or optronics,
i.e., no connected transmitters, receivers, regenerators, etc. (See
also-Dry Fiber)
Database
A multiuse collection of information (on a computer). Often
supports random access selectivity (via "Keys")
and multiple
"Views" or levels of abstraction of the
underlying data.
Data Circuits
Communication links that are optimized for digital transmission of
computer information
Day of Week Routing
Route calls based on day of week (e.g. single weekday, list
of week days, range of weekdays or combinations).
Day of Year Routing
Route calls based on month/day of the year (e.g. single day,
list of days, range of days or combination).
Db - See Decibel
DBMS - Data Base Management
System - See RDBMS, ODBMS
DCE - Data Communications
Equipment
DCS - Digital Cross-Connect
System (See DACS)
Digital European Cordless Telecommunications
A wireless standard for communications, operating at 1,88-1,9 GHz. The system is developed for high traffic rates and small cells. Applications are private, residential and business telephone and data transmissions.
Any switched telecommunication service (like 1+, 0++, etc.) that allows a
call originator to place long
distance calls directly to telephones outside the local service
area without an operator.
DDS - Digital Data Service
A digital data communication circuit (2.4, 4.8, 9.6 or 56K bps)
DE - Discard Eligible
Frame relay frame indicator that identifies that the frame may be
discarded in the case of network congestion.
Deactivation
A request to terminate service (or the process of terminating
service)
A unit of power (sound, electrical or optical) increase
(amplification) or loss (attenuation)
that is proportional to the exponential increase or decrease in
power.
Dedicated Line
A private line leased from a telecommunications carrier.
Default Carrier
Your regular Dial-1 carrier. Call 1-700-555-4141 to find your
default carrier.
Defense
Commercial Communications Office - DECCO
A Department of Defense organization that procures
communications circuits from carriers for use by the military and
certain other federal agencies.
Demarcation Point
- Demarc
A point (such as a jack or cross-connect panel) at which
ownership or responsibility for operating and maintaining facilities passes from one party to another.
Denied-Originating
Class - Terminating Only
Answer Only
Design Layout Record
Contains the layout for the local portion of a circuit at a
particular location.
Dial
To Place A Call On A Switched Network. The term "dial" is
obsolete - based on rotary dial phones and electromechanical relay
switches (which are nearly non-existent in modern telephone
systems.) Touch Tone service recognizes dual tones that are
generated as each telephone key is pressed. Where Touch Tone
service is not available, telephones and switches electronically
"pulse" signals that emulate the older rotary dial telephones. The
terms "place" a call or "originate" a call are more accurate than
"dial".
Dial Tone
Ready To Place/Originate A Call. When the off hook indication is received at a central office, a dial tone signal is sent to the originating
caller on a switched network to indicate that the switch is ready
to accept a number.
An optional feature on dedicated access lines (DALs).
DNIS delivers identifying digits (up to 14 digits) that distinguish
incoming calls. This allows CPE to
identify which number was dialed when multiple numbers terminate on
the same trunk group.
Dialer
Equipment that pulses out a standard dial protocol signal.
A device or method that uses discrete variations in voltage,
frequency, amplitude, location, etc. to encode, process, or carry
binary (zero or one) signals for sound, video, computer data or
other information. For example, a digital clock displays the time
as discrete numeric values, rather than angular displacement of
analog hands. Digital communications technology generally permits
higher speeds of transmission with a lower error rate than can be
achieved with analog technology. When analog signals are received
and amplified at each repeater station, any noise is also
amplified. A digital signal, however, is detected and regenerated
(not amplified). Unlike amplification, any noise (less than a
valid signal) is eliminated by digital regeneration.
Digit Stream
The switch signalling protocol that contains information such
as information digits, destination number, originating ANI, etc. The digit stream is defined by Bellcore standards.
Dim Fiber
A fiber optic system in which the carrier provides regenerators, but does not originate the optical signals at
one-or-both ends.
Direct Inward Dialing
- DID
A PBX or
Centrex optional feature that permits outside calls to be
placed directly to a station line without use of an operator.
Direct Inward
System Access - DISA
The ability to access a PBX from an
outside telephone number. For example, a caller might dial an
assigned number, input a security code and then use the PBX to place a long distance call.
Directory Assistance
- DA
An information service whereby operators assist customers in
obtaining the telephone number(s) they wish to call.
DISA - See Direct Inward
System Access
Disconnect
Call termination and the information associated with it such
as time of day, who disconnected (originator, destination, etc.)
Discount
Special pricing flexibility used to encourage increased use
of products, or to improve competitive marketing.
Distortion
A change (other than attenuation
or noise) in the characteristics of a signal due to the distance of
transmission or equipment problems or inefficiencies.
Distributed
Network Computing - DNC
Separation of the elements of an application into subcomponent
objects that can be implemented on multiple collaborative
computers on a common network. Objects are designed to optimize
local processing and storage capabilities and to minimize the
slower overhead of remote communication.
DLCI - Data Link Connection Identifier
A frame relay header field that identifies the destination of the
packet.
DLR - See Design Layout Record
DMOPRO
Switch Profile Loading. Northern Telecom DMS-250 process for
performing Network Database Updates. Defines the network
configuration, valid user ANIs, alternate
routing tables, service classes, etc.
DMS-250
Northern Telcom (NTI) Programmable Communication Switch.
Commonly used in the telecommunication industry.
DN - Directory Number
Usually 7 or 10 digits.
DNIC - Data Network
Identification Code
A four digit number used to identify public data networks.
DNIS - See Dialed Number
Identification Service
Dominant Carrier
A carrier with marketing power and the ability to control overall
price levels. LECs
and AT&T, are considered dominant.
Drag and Drop
A GUI concept that allows one screen object to be selected
and passed as input to another screen object (icon).
Drop and Insert
The ability to add and remove lower-level capacity from a
higher-level circuit at an equipment location. Lower-level capacity
may be interconnected at an intermediate point of a higher-
capacity circuit. For example, a Chicago to Los AngelesDS-3
might have DS-1 level drop and insert
capability at Salt Lake City. this would provide DS-1
service from Los Angeles to Salt Lake and from Salt Lake to
Chicago.
DS - Digital System
Circuit type
DS-0
(Facility) - The base unit of digital transmission capacity. 1
communication channel = 1 simultaneous voice grade equivalent with
a communication capacity of 64 thousand bits per second (64Kbps)
DS-1 (Facility)
T1- The equivalent of 24 multiplexed voice grade channels (DS-0s). 1.544 million bits per second (1.5Mbps)
DS-2 (Facility)
T2 - The equivalent of 4 multiplexed T1
channels. 6.312 million bits per second (6.3Mbps)
DS-3 (Facility)
T3 - The equivalent of 28 multiplexed T1
channels. 44.736 million bits per second (45Mbps)
DS-4 (Facility)
T4 - The equivalent of 6 multiplexed T33
channels. 274.176 million bits per second (274Mbps)
DSU - Digital Service Unit
A network interface device between the CSU and the customer's DTE.
Usually associated with a CSU, the DSU has a V.35, RS232, RS449, or
other interface to the customer equipment. The DSU is also a multiplexer
for FT1 circuits.
