DA

( Directory Assistance ) An information service whereby an operator or an automated system acts to assist customers in obtaining the telephone number(s) they wish to call. Directory Assistance may also be used to obtain postal mailing addresses and other information. To call Directory Assistance,  Dial 411, 1-555-1212, 1-(Area Code) 555-1212
See also: Operator Service Call

DAL

( Dedicated Access Line ) A non-switched circuit from the subscriber location to a carrier.

DDD

( Direct Distance Dialing ) 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  operator assistance.

Deactivation

A request to terminate service (or the process of terminating service)

Dedicated Access Line

Dedicated Line

A private line leased from a telecommunications carrier.

Default Carrier

The regular Dial - 1+ Long Distance Carrier  ( IEC ) on a specific line. Call 1-700-555-4141 from subscriber telephone line to determine corresponding default carrier for that line.

Dial

To Place a telephone 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 The term "dial" is obsolete - based on rotary dial phones and electromechanical relay switches (which are nearly non-existent in modern telephone systems.)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 ( DTMF ) 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".
See also DTMF, Outbound │Also, learn about: Call Placement in our Reference Section

Dial Tone

Ready To Place/Originate A Call. ( Dial a telephone number )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 CO switch is ready to accept a number. See also: Off Hook, Answer Supervision

Dialer

Equipment that generates a standard dial protocol signal.
See also: Dial, DTMF, Call Placement

Digital

A device or method that uses discrete variations in voltage, frequency, amplitude, location, etc. to encode, process, or transmit binary (zero or one) signals for sound, video, computer data, telecommunications transmissions 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 amplified as well. A digital signal, however, is detected and regenerated (not amplified). Unlike amplification, any noise (less than a valid signal) is eliminated by digital regeneration.

Directory Assistance

Direct Distance Dialing

( DDD ) 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  operator assistance.

Design Layout Record

( DLR )Official design of an inter-connection.

DLR

See Design Layout Record

DTMF ( Dual Tone Multi Frequency )

Abbreviation for Dual Tone Multi Frequency The system used by a touch-tone telephone whereas each of the 12 keys (10 numeric keys 0-9 and the symbol keys: # and * ) generate audible signals when pressed, each touch tone signal consisting of two separate tones ( Dual-Tones ). The twelve Dual-Tones of the twelve keys of a touch-tone key pad are made by from a combination of 7 individual tone / frequencies. A touch tone keypad is aligned in a grid with 4 rows and 3 columns.  There is a tone for each of the 4 rows and a tone for each of the 3 columns. 4+3=7 (  4 rows + 3columns = 7 Tones ) The Dual-tone generated by each key consists of the two tones that align to its row and column. 4X7=12 for 12 keys and 12 dual-tones. Each dual-tone is recognized &  identified by the switch at the central office when routing the telephone call.  See also: Dial, Outbound

More information about this subject

Dual Tone Multi Frequency  ( DTMF )

See DTMF, or Touch Tone

More Information on DTMF / Touch Tone Dialing

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