ISDN was designed in the mid-1970s as the telephone network of the future. It can carry voice calls and transfer data or graphics on the same call, or it could carry a videophone call with a "reasonable" quality picture.International availability of lines is increasingly widespread, and in two years' time ISDN will become the standard business line offering from BT. This will be an especially interesting time for accountants, as Andrew Baird, of specialist software company 4Sight Communications, explains.
Mr Baird is a chartered accountant who moved into the software business. Among the applications he foresees are remote auditing, where accountants could get instant access to their clients' accounting systems via an on-line data link. They would dialup, go to whichever part of the system they need, and call off selected files, such as a list of debtors. They could then analyse the data on their own computer: "Auditing remotely saves money and time, which is otherwise wasted by constantly going back and forth", he says.
Gerry Fletcher, of Comprador Communications, suggests voiceannotated balance sheets and accounts. "Imagine getting a client's accounts on your computer, with their voice explaining to you exactly what is going on and why. You could look at the data, listen to the comments, then do some modelling yourself, add your own comments and then send it all back to them, on-line."
Other accounting applications Baird and Fletcher suggest include year-end reconcilliations, electronic transfer of invoices, remote stock-taking using video terminals, and videoconferencing for discussions with senior management at a client.
Connecting a computer to ISDN is done via a terminal adaptor, which plugs into the computer on one side, and the ISDN phone socket on the other. Alternatively, an internal ISDN card can be used for most desktop computers.
A major benefit of ISDN is that it is a dial-up service, just like the ordinary phone network. So there is no need to pay expensive rental costs for dedicated lines which are only rarely needed - as on most corporate computer networks.
ISDN also provides high quality, fast transmission which can't be achieved using an ordinary modem connection - the usual way to date to exchange computer data on an ad hoc basis.
ISDN technology has been tested since the mid-1980s, but it is only in the past 12 months that BT and its counterparts in other countries have had ISDN lines widely available. BT and Mercury both offer competitive ISDN services, but despite dramatic price cuts during 1992, connections are anything but cheap.
BT offers two levels of service. The basic service comprises two phone lines per connection. The two can be used separately - only one line is needed for an ordinary conversation or data transfer - or they can be used together for applications that need a lot of line capacity, a videoconference call, for example.
The "primary rate" ISDN provides a block of a minimum of 30 lines, and is mostly used by large firms which connect it to a telephone switchboard. The lines can be used in groups of two or even four, to suit the application.
Mercury currently only offers a single level of service termed "primary rate". Both operators are currently battling it out by making special offers on their primary rate connection charges.
With a minimum of 15 lines per connection, BT's standard connection charges start at around #1,500 - ie #100 a line - plus an annual rental charge of #135 per line. But from 1 January to 31 March the connection charge has been dropped to #25 a line, reducing the minimum charge to #375 plus rental.
Mercury's annual rental charge is #114 a year. And although it usually charges #92 a line for connections (15 line minimum), it reduced its charges last year, and will be charging #26 a line until at least the end of February.
With these reductions BT and Mercury are hoping to make ISDN a viable alternative to an analogue business exchange line for the many small to medium sized companies who have previously found connection charges prohibitive.
Cost is naturally a key issue. And, as Alan Spencer, an independent consultant specialising in ISDN, says, even the basic connection charge at its present level (#400) prevents many companies from installing ISDN. "I've got three phone lines, to convert one of them to ISDN costs me #400. Am I going to do it?" The connection charge for analogue lines was reduced under the Oftel review of BT's prices last July to #99.
Until recently, the patchy connections between the national ISDN services meant that international ISDN calls weren't practical. However, international links are gradually being put in place by the phone companies. ISDN services outside the UK are available in Australia, Belgium, France, Germany, Japan, Holland, Sweden, Switzerland, and the US, where the largest number of connections are in place.
Tim Duffy, European manager of US-based videoconferencing supplier Picturetel, believes that the links have now improved to the point where the service is acceptable to several European countries and the US: "Most products we sell today go on to ISDN. That is different from one year ago".
But international ISDN standards remain a problem area, especially in Europe. Currently, all European networks operate to different technical standards.
In April 1989, a Memorandum of Understanding was signed by European carriers, which all agreed to install ISDN services to a common technical standard by 1 January 1993. These standards have not been approved, and indeed, parts of the specification have not even been written. The target date has now been moved to 1 January 1994.