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Technical Documents

  • SEP

    Different connection types to the internet

    Author: Technical Support
    Internet connections
  • DSL – Digital Subscriber Line

    DSL is frequently referred to as an "always on" connection because it uses existing 2-wire copper telephone line connected to the premise so service is delivered simultaneously with wired telephone service -- it will not tie up your phone line as an analog dial-up connection does. The two main categories of DSL for home subscribers are called ADSL and SDSL. All types of DSL technologies are collectively referred to as xDSL. xDSL connection speeds range from 128 Kbps to 9 Mbps.

    ADSL - Asymmetric Digital Subscriber Line

    ADSL stands for Asymmetric Digital Subscriber Line service. It is called asymmetric because the download and upload speeds are not symmetrical (download is faster than upload).


    ADSL2 (ITU G.992.3 and G.992.4) adds new features and functionality targeted at improving performance and interoperability and adds support for new applications and services. Among the changes are improvements in ADSL's data rate, an increase in the distance ADSL can reach from the local telephone exchange, dynamic data rate adaptation, better resistance to noise, diagnostics, and a stand-by mode to save power. ADSL2 also reduces the initialisation time from more than 10 seconds (as is required for ADSL) to less than 3 seconds. ADSL2 has the same signal footprint as ADSL.

    ADSL+2 - ADSL Extension

    ADSL2+ (ITU G.992.5) doubles the bandwidth used for downstream data transmission, effectively doubling the maximum downstream data rates, and achieving rates of 20 Mbps on telephone lines as long at 5,000 feet. ADSL2+ solutions will interoperate with ADSL and ADSL2, as well as with ADSL2+. ADSL2+ will include all the feature and performance benefits of ADSL2 while maintaining the capability to interoperate with legacy ADSL equipment.

    SDSL - Symmetric Digital Subscriber Line

    Symmetric digital subscriber line (SDSL) refers to digital subscriber line (DSL) technologies, that is, technologies for transmission of 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. This symmetric bandwidth can be considered to be the opposite of the asymmetric bandwidth offered by asymmetric digital subscriber line (ADSL) technologies, where the upstream bandwidth is lower than the downstream bandwidth. SDSL is generally marketed at business customers, while ADSL is marketed at private as well as business customers.

    VDSL - Very High DSL

    VDSL (Very High-Speed Digital Subscriber) uses the normal copper phone line to transmit data at a much higher frequency than ADSL. If you are within 1km of a capable roadside cabinet or exchange switching to VDSL Broadband will vastly increase your upload and download speeds.

    Cable - Broadband Internet Connection

    Through the use of a cable modem you can have a broadband Internet connection that is designed to operate over cable TV lines. Cable Internet works by using TV channel space for data transmission, with certain channels used for downstream transmission, and other channels for upstream transmission. Because the coaxial cable used by cable TV provides much greater bandwidth than telephone lines, a cable modem can be used to achieve extremely fast access. Cable providers typically implement a cap to limit capacity and accommodate more customers. Cable speeds range from 512 Kbps to 20 Mbps.


    Ethernet First Mile (EFM or Ethernet Internet) is a low cost leased line technology with huge cost savings over traditional fibre leased lines, bringing mission critical connectivity within the reach of small business. EFM provides symmetrical bandwidth at speeds of upto 20 Mbps with no contention. “Symmetrical” means the upstream and downstream speeds are the same, and uncontended means the bandwidth is not shared, so does not slow down, and remains consistent.

    Wireless Internet Connections

    Wireless Internet, or wireless broadband is one of the newest Internet connection types. Instead of using telephone or cable networks for your Internet connection, you use radio frequency bands. Wireless Internet provides an always-on connection which can be accessed from anywhere — as long as you geographically within a network coverage area. Wireless access is still considered to be relatively new, and it may be difficult to find a wireless service provider in some areas.

    T-1 Lines – Leased Line

    A leased line is a private bidirectional or symmetric telecommunications line between two or more locations provided in exchange for a monthly rent. Sometimes known as a private circuit or data line in the UK. Unlike traditional PSTN lines it does not have a telephone number, each side of the line being permanently connected to the other. Leased lines can be used for telephone, data or Internet services. Some are ringdown services, and some connect to PBXes. Typically, leased lines are used by businesses to connect geographically distant offices. Unlike dial-up connections, a leased line is always active. The fee for the connection is a fixed monthly rate. The primary factors affecting the monthly fee are distance between end points and the speed of the circuit. Because the connection does not carry anybody else's communications, the carrier can assure a given level of quality. An Internet leased line is a premium internet connectivity product, delivered over fiber normally, which is dedicated and provides uncontended, symmetrical speeds, full-duplex. It is also known as an ethernet leased line, DIA line, data circuit or private circuit. For example, a T-1 channel can be leased, and provides a maximum transmission speed of 1.544 Mbit/s. The user can divide the connection into different lines for multiplexing data and voice communication, or use the channel for one data circuit. Leased lines, as opposed to DSL, are being used by companies and individuals for Internet access because they afford faster data transfer rates and are cost-effective for heavy users of the Internet.

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