Glossary of Terms

ADSL

Asymmetric Digital Subscriber Line – the broadband service provided over normal BT analogue telephone lines. To receive ADSL your exchange has to be enabled for broadband and your line needs to be tested by BT. With ADSL you can access the Internet and use your telephone for voice calls at the same time.

ADSL modem

Unless an ADSL modem is already fitted to your PC, you will need one to connect between you PC and ADSL-enabled phone line in order to access the Internet. Note that ADSL is NOT compatible with ordinary dial-up modems. ADSL modems may be fitted inside your PC (PCI cards) or plus in externally to a USB port.

ORB offers a range of products to suit various home and business requirements. Click here for details.

ADSL router

If you wish to share your broadband connection between two or more PCs in a home or office network then you will need an ADSL router to connect your network to the Internet. ADSL routers are available which operate on wired or wireless home/office networks. ORB offers a range of products to suit various home and business requirements. Click here for details.

Bandwidth

Bandwidth is a measure of the capacity of a wired or wireless communications link to carry information. For data networks, bandwidth is measured in kilobits per second (thousands of bits per second or kbps) and megabits per second (millions of bits per second or Mbps).

ORB’s wireless broadband services run at 512kbps and 1Mbps in both directions. The ADSL services run at 512kbps and 1Mbps downstream and 256 kbps upstream. By comparison an ordinary dial-up connection runs at a maximum of 57.6 kbps.

Broadband

Broadband is high speed internet access. Prior to broadband most people accessed the internet through dial-up modems or ISDN (sometimes sold by BT as Home or Business Highway). These modes of access are termed “narrowband”. Broadband is between 10 and 40 times faster than these; plus it is always on, meaning there’s no waiting for a connection to be made or mail to be collected.

Up until a couple of years ago, broadband was prohibitively expensive and a practical proposition only to large organisations. Now broadband internet services are being made available to consumers and small businesses at much lower cost, comparable to the prices for existing narrowband internet access.

Contention ratio

With broadband some of the bandwidth is shared between other users. This is necessary to keep down the cost of the service and is possible because not all users are transferring data at the same time. Most of ORB’s services are shared or “contended” at a ratio of 50:1 which means that customers share the bandwidth with up to 49 other users. Thus the performance of a broadband connection can vary according how many other users happen to be online at that moment. In practice ORB manages the contention carefully to ensure that customers’ enjoy the best online experience.

DSL

Digital subscriber loop – the “subscriber loop” is the length of copper wire which runs from your house to the nearest exchange (often used in its generic form as xDSL, and has “types” like ADSL).

ISDN

Integrated Services Digital Network – a legacy digital telephone line service also sold by BT under the Business or Home Highway brand name. ISDN can be used for internet access at up to a maximum of 128kbps and is also used by small business for digital switchboards. ISDN is relatively expensive to run and is being phased out by broadband.

For customers with ISDN lines what wish to convert to broadband it is important to note that ADSL is only compatible with ordinary analogue telephone lines. If you have ISDN and want to use this for broadband it will have to be converted to analogue first. ORB can place this order on BT on your behalf, though it may be subject to an additional charge.

ISP

Internet service provider – organisation which makes available connection to the internet, and which charges for this service: note there are two activities going on here, being the connectivity (providing modems or routers to accept a call from your computer) and service or content provision (like hosting a website for you, or storing and forwarding your e-mail).

Microfilter

Also known as “splitters”. If you have ORB’s ADSL service then you will need an ADSL microfilter for each phone socket around your premises which is connected to the ADSL line. The splitter separates the ADSL (high frequency) signals from the analogue (low frequency) signals used by your telephone.

Modem

MOdulator-DEModulator – a device for changing computer signals (which are digital) into sound (analogue) and back again, and which thus allows your computer to use a voice circuit