Ten years ago, students of telecommunications engineering were told modems were a dying technology and that digital phone lines in the shape of ISDN were about to take over. But, as is common in the IT industry, nothing happened. ISDN remained backstage for several years and is only now striding into the limelight.

Well, more stumbling than striding, according to some IT managers, who blame the telephone companies for the slow take-up of a valuable business service.

Getting an ISDN connection is still considerably more expensive and takes longer than a traditional telephone line, and some have complained of poor service after installation. Additionally, there has been much confusion over Telecom Eireann's plans to reduce ISDN costs to those of analogue telephony. For the uninitiated, ISDN, or integrated services digital network, is basically a digital telephone line, designed to replace traditional analogue lines into houses and businesses. Being digital, it offers cleaner, faster connections.

There are two types: basic rate, which gives two 64 kbps (kilobits per second) links, and primary rate, which gives 30 such channels. ISDN services have been available from Telecom Eireann since 1994.

Basic rate ISDN is particularly attractive to homes and small businesses, giving an extra line (with its own number) and direct dialling to extensions (DDI). Primary rate ISDN allows for up to 100 DDI extensions.

Part of the current confusion arises from a newspaper interview last January, in which Telecom Eireann chief executive, Mr Alfie Kane, reportedly promised that by the middle of this year there would be no price difference between providing (basic rate) ISDN services to consumers and providing copper wire services.

But ISDN installation and line rental is still considerably higher. While a domestic phone line costs £99 to install, with £12.10 monthly rental (inclusive of 21 per cent VAT), basic-rate ISDN costs £348 to install, with £29 monthly rental, exclusive of VAT.

Telecom Eireann's charges for primary-rate ISDN are £3,840 for set-up, and £290 for monthly rental.

A spokeswoman for Telecom Eireann suggested to The Irish Times that Mr Kane was misrepresented in last January's interview, but, she said, the company was finalising new price plans for ISDN connection and rental.

However, there will be no announcement until the telecommunications regulator's office approves the plans, she said.

While the higher set up and rental charges are undoubtedly a disincentive for would-be homeISDN users, they are not too big a burden for most businesses.

However, long lead times on installation and poor backup service are more serious, leading to criticism that Telecom Eireann isn't coping with the current demand for the decade-old technology.

Mr Roland Keogh, operations manager for Murray's Europcar, said he had experienced a series of delays and problems with the car rental company's ISDN lines. Among his complaints are excessive delays on installation, faulty service and an absence of a fault repair service at weekends.

He said the company ordered ISDN lines in Dublin, Shannon and Cork airports last December, and was told by Telecom Eireann that installation would take eight weeks.

However, when nothing had happened in this timeframe, the company raised the issue and finally got service on the three over a period from March to May.

In its Dublin offices, Murray's has also had problems with a primary-rate ISDN line in Baggot Street and another ISDN line in Stillorgan.

Mr Keogh's opinion is that Telecom Eireann is "bursting at the seams with ISDN orders" and is struggling to keep up. He said ISDN had a slow initial take-up, but that demand has rocketed in the last 18 months or two years.

Telecom Eireann said ISDN demand this year was up 300 per cent on last year, which indeed is more than was anticipated.

With nearly three-quarters of this demand in Dublin, the company conceded there were problems with lead times, but new account management procedures and new technologies - agreed under the employee share-option scheme (ESOP) - should address these problems.

The company said it planned to launch an ISDN service agreement plan later this year or early next year. This will give 24-hour, seven-day-a-week service, but will involve an additional fee.

Significantly, Esat Telecom said it would consider offering direct basic-rate ISDN services next year. It has been offering primary-rate service since earlier this year.

Mr Keogh's experiences are not isolated. Other business users, who prefer not to be named, have reported similar problems, especially long delays on installation times.

Meanwhile, home computer users are complaining that the setup and rental charges are prohibitive. As well as Telecom Eireann charges, the ISDN equivalent of a modem costs from about £150.

Yet ISDN is being promoted for home Internet use, particularly by Telecom Eireann's subsidiary, Indigo. Its £19.99 per month isn't the cheapest on the market (Club Internet, for example, charges £10 per month), but as these charges are on top of Telecom Eireann's standard ISDN charges, it's not surprising that Telecom says there are still very few domestic users.

Indigo's ads also claim ISDN offers "six times the speed", but an Indigo sales representative admitted this figure was based on users who have 9600 bps modems. With many people now getting speeds of between 33 kbps and 56 kbps, the advantages are more related to having an extra phone line and shorter call set-up times.

So, while DDI and improving availability ensure ISDN will continue to grow in popularity among small and medium enterprises, the market for home users is not likely to grow as quickly.

However, with new technologies in the pipeline, such as cable modems and ADSL (asymmetric digital subscriber lines), home users will not be limited to 56 kbps modems for too long.

Eoin Licken is at elicken@irish-times.ie