ISDN

Integrated Services Digital Network is the most common form of digital phone system in the UK. Technically it comes in two forms from BT (ISDN2e aimed at homes and small businesses and ISDN30 aimed at larger firms). Most homes that have it are supplied with BT home highway, which is a special version that includes a white box that gives you analogue and digital sockets.

Home Highway uses a normal copper wire connection to the house. But one does have to be within three miles of an exchange before one is be able to convert a line over. BT have to do a survey but over 90% of homes do pass.

The white box has to be mounted within thirty metres of your existing master socket. You normally keep your analogue number, and are given a second analogue line and a digital line numbers. What you effectively get though are two channels. You can make or receive phone calls on both analogue lines, or surf the net on one digital line and speak on one analogue line, or surf the net a double speed on the digital line but lose the analogue channels. You have four sockets on the box but can only ever actively use two at the same time.

Effectively you pay the same price in rental as those people who have two normal lines, but with many more connection possibilities. Even if one didn't use the digital connection at all, for some people it would be a better value than two normal lines since you can plug a normal modem into the analogue sockets and get a very clean high speed connection. One can buy a BT speedway card for less than fifty pounds and these allow 64k or 128k surfing with near instant connection.

Not all ISPs allow 128k connections however, and if you do use both channels BT will charge you double the per minute rate, which is a rather cheeky. Also if you have select services like call waiting you will have to pay for them separately on each line. International data calls are also charged at a higher price than for analogue calls. You do get your normal discounts, like friends and family, but as this site shows it is always cheaper to use an alternative supplier for voice calls, like AXS.

Send email to questions at callforless.co.uk
Last modified: April 15, 2002

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