A legal ruling on whether Meteor can proceed to roll out a mobile phone network will be announced on Monday. There is growing speculation that the High Court will affirm the decision to award the third mobile phone licence to the company.

A legal challenge by British company, Orange, the unsuccessful second bidder for the licence, has delayed the process by more than a year.

Ms Justice Macken, who heard the case, is to give her ruling on Monday afternoon but it may be subject to further appeal.

There is a growing expectation within the industry that she will uphold the decision of the telecommunications regulator, Ms Etain Doyle, to award the licence to Meteor. However, she may criticise elements of how Ms Doyle's office handled the process.

The hearing, which began in March, is said to have been the longest-running High Court action this year. Orange appealed the director's decision to refuse to grant it a licence and much of the court's time was taken up with complex legal argument.

Meteor's majority shareholder is US-based Western Wireless International, which has 60 per cent, Irish-owned RF Communications (30 per cent) and the US Walter Group Consultancy (10 per cent).

Tenders for the third mobile licence were submitted early last year, but there were only two bidders. Orange was said to be bitterly disappointed. It had been viewed in industry circles as favourite to win the bid. Shortly after the result was announced, the company initiated legal proceedings.

The Office of the Director of Telecommunications Regulation declined to comment on the matter yesterday. However, earlier this year, Ms Doyle said she was "quite confident" of the process by which the licence was awarded to the Meteor consortium and pledged to vigorously defend the Orange action.

The dispute has delayed the entry of a third operator and has effectively allowed a duopoly - Eircell and Esat - to operate with little reduction in call pricing.

Some industry observers say it will be very difficult for Meteor, if the licence award is upheld, to break into the market. They argue that the existing operators have gained huge numbers of subscribers and have built considerable brand awareness.

Eircell has more than 645,000 customers while Digifone has in excess of 370,000. Both operators have a mixture of pre-paid and subscriber customers.

However, one source who has studied the market closely says a business case still exists for the new operator provided it does not build out a complete telecommunications network. Success is also said to be dependent on it obtaining one of the next generation of mobile licences which will allow operators to carry large amounts of data via mobile phones.

The licence on offer combines GSM and DCS-1800 technologies which are suitable for use around built-up areas. Both Eircell and Digifone will be allowed to use DCS-1800 licences with their existing GSM ones. However, it is thought the third mobile operator will use one of the existing players' networks for coverage in areas it does not have a presence itself.

It is expected to take a third operator a minimum of nine months to build a network and it is only then that prices should begin to fall.