The attack on a rural telephone exchange in north County Cork last week was the first time organised criminals have targeted an exchange in order to disable telephone-based alarm systems. In doing so they set off alarms which quickly led to a Garda chase.

Significant though the attack was, the ensuing publicity is also likely to be significant for the security alarm business. By reminding people that telephone links to alarms are vulnerable, the attack is likely to encourage people to consider more robust links to monitoring stations. In the cat and mouse game where new security technology is followed by new security-breaking technology, businesses are now using advanced digital lines and radio channels which are harder to cut.

But how robust are these technologies, and how widespread are they? Phonewatch, for example, supplies a product which uses a cellular link for higher security. Called Eirlink, it was originally built to order but is now available as a commodity product, and uses Eircell's mobile network to transmit SMS (short messaging service) messages to the company's monitoring station in Sandyford, County Dublin.

Because SMS doesn't require as strong a signal as voice channels, Mr Nick Quigley, Phonewatch's chief executive, says the system works even in areas of poor cellular coverage.

But costing "just under £500", Mr Quigley admits less than 10 Eirlink products have been installed so far, and says it is primarily geared at the business market. The monthly monitoring charge is also higher than for the landline product - £19.50 per month (including cellular charges) against £11.50 per month. Big businesses, he noted, commonly use their own secure data networks for alarm monitoring.

Industry insiders say the Irish market in backup alarm links is quite unique in that long-range radio is traditionally very popular. Pre-dating cellular backup, such systems use radio links to send out alarm signals, typically via one of the myriad masts spiking up from the top of the Three Rock mountain overlooking Dublin, for example. However, with radio spectrum becoming a scarce commodity, and the Three Rock resembling more a hedgehog than a mountain, alternatives will be necessary.

For example, in Britain, Mr Quigley says, monitored digital lines are very popular. One such product there, called Redcare, alerts the monitoring station if lines are cut. Effectively this means the monitoring station is constantly checking the state of the line, taking the role of a security guard doing digital rounds, as it were.

One of the biggest independent alarm monitoring companies, Bell Communications, says that while long-range radio is the most popular form of backup channel here, cellular will catch up. Its technical sales director, Mr Peter Kelly, estimates that of the 90,000 people availing of monitoring in Ireland, 2,500-3,000 are availing of some form of radio backup.

Mr Kelly predicts cellular will become the more popular backup technology due to lower hardware costs, even though its running costs are higher. Long-range radio is free to use, he says, while cellular links involve rental and call charges. But the cost of cellular monitoring equipment has fallen from more than £1,000 for custom-made products to around £600 for off-the-shelf products.

Both Mr Quigley and Mr Kelly predict the prices of cellular backup products will continue to fall. "The technology will develop and the price will be pushed down," says Mr Quigley, adding that in the US there are now alarm products using mobile telephony costing between $200 (£131) and $300 .

Interestingly, one of the earliest cellular alarm products in the US was marketed by an Irish company, Europlex, which develops alarm control equipment. Its marketing director, Mr Ian Jackson, explains that three years ago Europlex licensed SMS alarm technology from Atlanta-based Cellemetry, a joint-venture set up by Bell South and another company called Numerex, marketing a cellular-phone product which plugged into alarm control panels.

Though Europlex is no longer involved, Cellemetry continues to sell cellular as well as satellite monitoring products. Meanwhile, Dublin-based Europlex now produces cellular telephone boards which slot inside its Adplex burglar and fire alarm controllers. Mr Jackson says about a quarter of the 4,000 or so Adplex products sold annually use the cellular product. Adplex costs $700-$800, with an additional $300-$400 for the cellular board, and 80 per cent of the market is abroad.

Mr Kelly says the increasing popularity of radio backup is driven partly by insurance companies which insist on it in high-risk areas or where there has been a break-in.

But, as ever, what technology giveth, technology taketh away. Already there are devices on sale in Asia which can jam mobile telephones within a radius of several metres.

Although illegal to use here, breaking communications regulations will hardly deter someone who is already trying to bypass an alarm system.

Eoin Licken is at elicken@irish-times.ie