An index of all the common telecoms terms, jargon and acronyms.

Telecommunications Glossary > D


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Default Routing

The ability of the switch to continue the call based on the dialled number, when the SCP cannot be accessed due to abnormal circumstances.

DSP – Digital Signal Processor

A digital microprocessor that calculates digitised signals that were originally analogue (e.g. voice) and then sends the results on. DSPs are used in telecommunications for tasks such as echo cancellation, call progress monitoring, voice processing and for compression.

DN – Directory Number

A unique complement of digits associated with the name of a subscriber in a telephone directory – i.e. your phone number.

DLC – Digital Loop Carrier

An access provisioning system by which a telephone switch is able to remotely deploy telephony interfaces to customers. Typically the connection between the switch and the DLC is via a digital or fibre connection, and user interfaces such as POTS (analogue) lines are deployed out of the DLC to customers.

DSL – Digital Subscriber Line

DSL is the technology that’s employed between a customer’s location and the carrier’s network, which enables more bandwidth to be provided by using as much of the existing network infrastructure as possible.

DSLAM – Digital Subscriber Line Access Multiplexer

A network device at a telephone company central office that receives signals from the multiple customer DSL connections, and puts the signals on a high-speed backbone line using multiplexing techniques.

Donor Exchange

The switch the directory number was initially ported from.

DTMF – Dual Tone Multi-Frequency

A term used to describe push button or touchtone dialling.


If you require any further information about any of the terms or information on our website, please call us on +44 (0)203 006 1170 or email contact@carritech.com.


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