Internet access terminology can be very confusing, especially if you’re trying to choose a new ISP. Each technology has its differences and some may be better at certain tasks than others, consequently it is important for consumers to understand the advantages and disadvantages of each prior to choosing a provider. This page seeks to explain the methods using simple language and is best used in conjunction with our 'Jargon Buster' section.

Narrowband Dialup

Dialup is one of the oldest forms of Internet access technology, which uses a simple adaptor known as a modem (modulating demodulator) to plug directly into a standard telephone line (POTS). The modem converts a computers digital data signal into a transmission that can be sent over the voice line for communication with a remote computer or ISP. Naturally, unless an unmetered (free calls) provider is chosen, usage will incur the standard voice call charges of your existing telecoms operator for every minute of use.

Sadly this form of Internet access is extremely slow and highly susceptible to line interference, running at a theoretical maximum of up to just 56Kbps (Kilobits per second) downstream and 48Kbps upstream using the latest (last) v.92 standard (details). Thankfully its ability to plug in to almost any phone line makes it very flexible and useful as a temporary backup solution for when your broadband service fails, though you can not make separate voice calls while using it.

Narrowband ISDN

Integrated Services Digital Network (ISDN) initially works in a similar way to dialup by connecting to a standard telephone line. However unlike dialup, ISDN is almost entirely digital and able to send information at speeds of up to 64Kbps downstream and upstream. This can be increased to 128Kbps using a second channel via an additional telephone line, otherwise known as ‘bonding’.

Sadly the technology often required a line to be converted from analogue to digital and two channels were needed for maximum speed, incurring additional costs. ISDN’s advantages were that it ran through a stable and highly reliable digital network, meaning that you always got the performance expected, though ISP side congestion could still hamper quality. BT's consumer ISDN products (HomeHighway, Midband) could also connect to dialup ISP's (see above).

Broadband DSL (ADSL, SDSL etc.)

DSL (Digital Subscriber Line) is a common technology for bringing high-bandwidth (broadband) information to homes and small businesses over standard (copper) telephone lines. DSL comes in many different flavours, such as the more common ADSL, SDSL and VDSL types. The most common form of DSL in the UK, ADSL (Asymmetric DSL), splits a single telephone line into separate voice and data channels, allowing you to make a phone call while surfing the Internet at the same time.

ADSL is capable of delivering speeds at up to 8Mbps (Megabits per second) downstream and 448Kbps upstream (832Kbps on shorter lines). The technology is cheap, fast and reasonably reliable, although performance can suffer due to ISP congestion, distance from the local exchange, interference and each connection is fixed to a single specific telephone line. Meanwhile newer ADSL2+ technology is capable of pushing speeds at up to 24Mbps; further examples below:

• ADSL: Asymmetric DSL devotes most of its two-way, or duplex bandwidth, to the downstream direction, sending data to the user. Only a small portion of bandwidth is available for upstream.
• VDSL: Very High Bit-rate DSL promises much faster speeds over relatively short distances (up to 50Mbps+ downstream over lines of 300 meters in length and up to 12Mbps upstream). VDSL may act as an extension to a fibre network and could one day replace ADSL2+.
• SDSL: Symmetric DSL is similar to HDSL with a single twisted-pair line, carrying 1.544 Mbps (U.S. and Canada) or 2.048 Mbps (Europe) each direction on a duplex line. It's symmetric because the data rate is the same in both directions.

Broadband Cable (Fibre)

Cable defines a network that uses robust fibre (optic or coaxial) cabling to connect its network with consumers, which can carry significantly larger amounts of data than a standard copper telephone line (POTS). This enables operators to deliver Internet access, television and phone services over a single connection. In addition, cable broadband services can theoretically be pushed far faster than POTS based DSL (e.g. ADSL) technologies, potentially reaching 100Mbps or higher in the future.

Most cable networks install fibre to a node (cable’s equivalent of a telephone exchange) and then deliver their connection to homes via a short run of copper wire. Future Fibre To The Home (FTTH) style services will deliver the cable directly to your doorstep. Cable coverage is often limited to towns and cities due to the costly nature of digging up roads for its installation, yet the service itself is usually well priced and comparable to DSL alternatives.

Broadband Wireless (Wi-Fi, WiMax)

Wireless ISP’s (WISP) use specific frequencies of the radio spectrum to transmit their signals through the air in the same way as a mobile phone network operates, doing away with wires. WISP’s comes in two different forms, a ‘fixed’ wide-area network or 'Hotspot'. Fixed networks are stationary and designed to deliver Internet access over wide areas, while Hotspots are cheaper localised methods of Internet access that have been designed to cover smaller areas, such as train stations or restaurants.

Presently there are two primary technology types, Wi-Fi (802.11) and WiMAX (802.16). Both can be used for the same purposes, although Wi-Fi is a far more domestic technology, often used in home networks and Hotspots. Meanwhile WiMax has been specifically designed for wider area high-speed networking. The latest hardware can push speeds at up to and over 100Mbps, although wireless performance reduces over distance and as it passes through solid structures.

Broadband Satellite

Satellites are effectively small autonomous space stations that can be placed in orbit around our planet and used as specialised wireless transceivers (receiver/transmitters) to relay information between different points on the ground. Their high altitude above the Earth gives them excellent coverage, which is especially useful in remote areas, though the technology can often be both costly and confusing to consumers.

Performance is known to be quite variable and satellite is no good for multiplayer gaming due to the time it takes for signals to go from the Earth to the satellite and back again (high latency). Satellite Internet access typically works in one of two different ways:

• One-Way: This cheaper option sees the satellite ONLY handling downstream (download) data by allowing you to dial in via a normal land based ISP (e.g. dialup) to handle the upstream (upload) requests for data.
• Two-Way: With the more expensive two-way option the satellite handles everything; there's no need for an additional Internet connection.

Mobile Broadband (3G [UTMS] / 3.5G [HSPA] / 4G [Mobile WiMax | LTE])

This represents wireless data communication technologies that utilise mobile phone radio spectrum to deliver Internet access almost anywhere thanks to the wide coverage. The service can usually be accessed through a mobile phone, although many modern data-only packages will deliver it through a USB adaptor or PCMCIA data card.

Speeds range from 3G’s 384Kbps (Kilobits per second) to 3.5G’s (HSPA) 14Mbps+ (Megabits per second) downstream and could go much faster in the future. Such services are usually restrictive, limiting access to specific services and imposing harsh data usage caps. However recent moves have seen prices coming down to almost fixed-line levels and increasingly flexible usage policies.