Digital subscriber line

DSLxDSLDigital Subscriber Line (DSL)DSL internetDSL Service64 kbs lineADSL/SDSLbroadbandBroadband modembusiness DSL
Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines.wikipedia
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Asymmetric digital subscriber line

ADSLAsymmetric DSLADSL
In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access. Employees at Bellcore (now Telcordia Technologies) developed asymmetric digital subscriber line (ADSL) by placing wide-band digital signals at frequencies above the existing baseband analog voice signal carried on conventional twisted pair cabling between telephone exchanges and customers.
Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide.

Symmetric digital subscriber line

SDSLSymmetric DSLsymmetric
In symmetric digital subscriber line (SDSL) services, the downstream and upstream data rates are equal. Engineers developed high speed DSL facilities such as high bit rate digital subscriber line (HDSL) and symmetric digital subscriber line (SDSL) to provision traditional Digital Signal 1 (DS1) services over standard copper pair facilities.
A symmetric digital subscriber line (SDSL) is a digital subscriber line (DSL) that transmits digital data over the copper wires of the telephone network, where the bandwidth in the downstream direction, from the network to the subscriber, is identical to the bandwidth in the upstream direction, from the subscriber to the network.

DSL filter

ADSL splitterPOTSsplitter
On the customer premises, a DSL filter on each non-DSL outlet blocks any high-frequency interference to enable simultaneous use of the voice and DSL services. On the subscriber's end of the circuit, inline low-pass DSL filters (splitters) are installed on each telephone to filter the high-frequency signals that would otherwise be heard as hiss, but pass voice frequencies.
The DSL filter prevents interference between such devices and a digital subscriber line (DSL) service connected to the same line.

Telephone line

phone linelinetelephone cable
Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines.
Telephone lines are used to deliver landline telephone service and Digital subscriber line (DSL) phone cable service to the premises.

DSL modem

ADSL modemDSL modemsDSL
The two main pieces of equipment are a digital subscriber line access multiplexer (DSLAM) at one end and a DSL modem at the other end.
A digital subscriber line (DSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line service for connection to the Internet, which is often called DSL broadband.

ISDN digital subscriber line

IDSL
The motivation for digital subscriber line technology was the Integrated Services Digital Network (ISDN) specification proposed in 1984 by the CCITT (now ITU-T) as part of Recommendation I.120, later reused as ISDN digital subscriber line (IDSL).
ISDN Digital Subscriber Line (IDSL) uses ISDN-based digital subscriber line technology to provide a data communication channel across existing copper telephone lines at a rate of 144 kbit/s, slightly higher than a bonded dual channel ISDN connection at 128kbit/s.

Broadband

Broadband Servicesbroad-bandBroadband Internet
The 1980s saw the development of techniques for broadband communications that allowed the limit to be greatly extended.
The various forms of digital subscriber line (DSL) services are broadband in the sense that digital information is sent over multiple channels.

ADSL loop extender

loop extenders
But ADSL loop extenders increase these distances by repeating the signal, allowing the LEC to deliver DSL speeds to any distance.
A DSL loop extender is a device that a telephone company can place between subscriber premises equipment and central office interfaces to extend the distance and increase the channel capacity of digital subscriber line (DSL) connections.

Multiprotocol Label Switching

MPLSLabel Switched PathLabel Switch Router
Once upstream and downstream circuits are established, a subscriber can connect to a service such as an Internet service provider or other network services, like a corporate MPLS network.
MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL.

Joseph Lechleider

Joseph W. Lechleider
Joseph W. Lechleider's contribution to DSL was his insight that an asymmetric arrangement offered more than double the bandwidth capacity of symmetric DSL.
Joseph W. Lechleider (22 February 1933, Brooklyn – 18 April 2015) was the inventor at the Bell Telephone Company of the DSL (digital subscriber line) technology.

Internet service provider

ISPInternet service providersISPs
Once upstream and downstream circuits are established, a subscriber can connect to a service such as an Internet service provider or other network services, like a corporate MPLS network.
However, cable television companies and the telephone carriers already had wired connections to their customers and could offer Internet connections at much higher speeds than dial-up using broadband technology such as cable modems and digital subscriber line (DSL).

Dry loop

alarm circuitBasic analog loopdry pair
Early DSL service required a dedicated dry loop, but when the U.S. Federal Communications Commission (FCC) required incumbent local exchange carriers (ILECs) to lease their lines to competing DSL service providers, shared-line DSL became available. A naked DSL (also known as standalone or dry loop DSL) is a way of providing DSL services without a PSTN (analogue telephony) service.
A dry pair was originally used with a security system but more recently may also be used with digital subscriber line (DSL) service or an Ethernet extender to connect two locations, as opposed to a costlier means such as a Frame Relay.

Naked DSL

Standalone DSLDry-loop DSLStand-alone DSL
A naked DSL (also known as standalone or dry loop DSL) is a way of providing DSL services without a PSTN (analogue telephony) service.
A naked DSL, also known as standalone or dry loop DSL) is a digital subscriber line (DSL) without a PSTN (analogue telephony) service — or the associated dial tone.

Low-pass filter

low-passlow pass filterlowpass filter
On the subscriber's end of the circuit, inline low-pass DSL filters (splitters) are installed on each telephone to filter the high-frequency signals that would otherwise be heard as hiss, but pass voice frequencies.
Telephone lines fitted with DSL splitters use low-pass and high-pass filters to separate DSL and POTS signals sharing the same pair of wires.

Telephony

digital telephonytelephonedigital
A naked DSL (also known as standalone or dry loop DSL) is a way of providing DSL services without a PSTN (analogue telephony) service. It is useful when the customer does not need the traditional telephony voice service because voice service is received either on top of the DSL services (usually VoIP) or through another network (mobile telephony).
In the second half of the 20th century, fax and data became important secondary applications of the network created to carry voices, and late in the century, parts of the network were upgraded with ISDN and DSL to improve handling of such traffic.

Digital subscriber line access multiplexer

DSLAMDSLAMsDSL access multiplexer
The two main pieces of equipment are a digital subscriber line access multiplexer (DSLAM) at one end and a DSL modem at the other end.
A digital subscriber line access multiplexer (DSLAM, often pronounced DEE-slam) is a network device, often located in telephone exchanges, that connects multiple customer digital subscriber line (DSL) interfaces to a high-speed digital communications channel using multiplexing techniques.

Loading coil

load coilloading coilsPupin coil
Because DSL operates above the 3.4 kHz voice limit, it cannot pass through a load coil, which is an inductive coil that is designed to counteract loss caused by shunt capacitance (capacitance between the two wires of the twisted pair).
If the telephone line is subsequently reused to support applications that require higher frequencies, such as in analog or digital carrier systems or digital subscriber line (DSL), loading coils must be removed or replaced.

High-bit-rate digital subscriber line

HDSLhigh bit rate digital subscriber line
Engineers developed high speed DSL facilities such as high bit rate digital subscriber line (HDSL) and symmetric digital subscriber line (SDSL) to provision traditional Digital Signal 1 (DS1) services over standard copper pair facilities.
It was the first digital subscriber line (DSL) technology to use a higher frequency spectrum over copper, twisted pair cables.

Backhaul (telecommunications)

backhaulbackhaul networkbackhauling
By 2012, some carriers in the United States reported that DSL remote terminals with fiber backhaul were replacing older ADSL systems.

Wi-Fi

WiFiwireless internetwireless
The standard way to let multiple computers share a DSL connection uses a router that establishes a connection between the DSL modem and a local Ethernet, Powerline, or Wi-Fi network on the customer's premises.
Routers often incorporate a digital subscriber line modem or a cable modem and a Wi-Fi access point, are frequently set up in homes and other buildings, to provide Internet access and internetworking for the structure.

Qwest

Qwest CommunicationsQwest Communications InternationalQwest Communications International, Inc.
It started making a comeback in the United States in 2004 when Qwest started offering it, closely followed by Speakeasy.
The Wireline Services segment provided local voice, long distance voice, and data and Internet (DSL) services to consumers, businesses, and wholesale customers, as well as access services to wholesale customers.

Telephone exchange

exchangescentral officeexchange
Employees at Bellcore (now Telcordia Technologies) developed asymmetric digital subscriber line (ADSL) by placing wide-band digital signals at frequencies above the existing baseband analog voice signal carried on conventional twisted pair cabling between telephone exchanges and customers.
These devices are used to provide service where existing copper facilities have been exhausted or by siting in a neighborhood, can reduce the length of copper pairs, enabling digital services such as Integrated Services Digital Network (ISDN) or digital subscriber line (DSL).

ITU-T

CCITTITU Telecommunication Standardization SectorTelecommunication Standardization Sector
The motivation for digital subscriber line technology was the Integrated Services Digital Network (ISDN) specification proposed in 1984 by the CCITT (now ITU-T) as part of Recommendation I.120, later reused as ISDN digital subscriber line (IDSL).

Voice over IP

VoIPVoice over Internet Protocolvoice-over-IP
It is useful when the customer does not need the traditional telephony voice service because voice service is received either on top of the DSL services (usually VoIP) or through another network (mobile telephony).
An alternative to preemption on slower links, such as dialup and digital subscriber line (DSL), is to reduce the maximum transmission time by reducing the maximum transmission unit.

DOCSIS

cableDOCSIS 3.0EuroDOCSIS 3.0
Telephone companies were pressured into moving to ADSL largely due to competition from cable companies, which use DOCSIS cable modem technology to achieve similar speeds.
A typical CMTS is a device which hosts downstream and upstream ports (its functionality is similar to the digital subscriber line access multiplexer (DSLAM) used in a digital subscriber line (DSL) system).