ADSL trials between Eircom and other operators will begin on Monday but a number of technical difficulties, costing issues and regulatory uncertainties threaten to delay the commercial roll-out of the technology.

Although Eircom has researched ADSL with former partners such as Future TV over the past two years, the company remains coy about setting a definitive launch date. Sometime between April and September is the latest prediction.

Eircom's belief that it needs to offer television services as part of an ADSL bundle of services to attract customers is a major regulatory issue that could derail ADSL deployment.

Cable operators NTL and Chorus claim they have exclusive legal rights to broadcast television over their own networks until 2004.

Telecoms regulator Ms Etain Doyle could face expensive legal battles, which would delay the roll-out of ADSL, if she changed this exclusivity.

Last month she side-stepped the crucial decision by ordering a "comprehensive review" of ADSL services.

Eircom is threatening to pull investment in its ADSL services if it is not allowed to provide TV services.

An Eircom decision to delay or cancel its planned ADSL investment would have serious repercussions. Eircom's proposed costs to enable other operators to access its local network - €32.50 (£25.60) line rental per month and €484 for connection - are among the highest in the world. Other operators need such access to provide their own ADSL services.

Eircom would have little reason to compromise on local access issue (known as unbundling the local loop) if it could not offer its own ADSL service. Eircom's ownership of the local network will make it extremely difficult for competitors to enter the ADSL market.

Earlier this week Mr Neil Parkinson, the outgoing chief executive of Esat Telecom, criticised Eircom, saying it was not providing enough information on unbundling and that its proposed charges for access were too high. He said this would delay Esat's ADSL strategy until late 2001.

Most telecoms experts believe further difficulties with the unbundling process are likely to arise during the year. Access to exchanges, technology and service agreements could all be potential problem areas. In addition to these regulatory and costing issues, a range of technical problems could also delay ADSL deployment.

"Some technical and physical problems have to be ironed out, such as quality of the line and cross talk - a type of interference caused when copper lines are close together," says Mr David Gilligan, a telecoms consultant with Mason Communications.

"The distance between the nearest telephone exchange and the end user can also restrict ADSL. The system works best to approximately two miles," he says.

These problems are common to all international operators and have been one of the main reasons for a comparatively slow roll-out of ADSL services in Europe.

But an internal Eircom document seen by The Irish Times highlights that weaknesses in Eircom's "operational processes" would prevent the company from offering a full complement of ADSL services at present.

"Eircom's view is that the current level of reliability of its access network. . . is not at a satisfactory level for the provision of digital television services," says the document.

The document says competition would force Eircom to "substantially improve its performance in terms of reliability of its access network through adaptation of new operational processes".

One expert with an intimate knowledge of Eircom's ADSL capabilities said these issues could impede a future roll out.

Operators in European countries such as France, Germany, the UK and even Hungary already offer commercial ADSL services. A failure by Eircom to offer a reliable service shortly would undermine the Republic's claims to be an ecommerce hub.

This would be a serious embarrassment for the Government, which has been extolling the virtues of Ireland's e-commerce potential. It would hurt business and small firms who face lengthy delays in obtaining ISDN lines and are eager to exploit ADSL services with "always on" Internet services.

The availability of "always on" Internet in the US has been a factor in its rapid adoption of the Internet. The Government's dream of an e-society could die with an incumbent operator unwilling or unable to provide ADSL services.