The High Court has found that Eircell does not have a dominant position in the Irish mobile phone market but is guilty of a number of breaches of contract with airtime service provider Meridian.
Meridian is now expected to pursue an action for damages against Eircell.
The action brought by Meridian against Eircell was the longest commercial case in the State's history, lasting 94 days.
Meridian and its wholly owned subsidiary, Cellular 3, operate the Imaginemobile phone service which has about 20,000 mobile phone customers in the State.
Imaginesupplies these customers by reselling airtime, which it buys in bulk from Eircell through a volume discount agreement set almost 40 per cent below normal rates.
A statement from Eircell today said it is "delighted" that the allegations of dominance and abuse of its position had been rejected by the High Court. But the company expressed disappointment that the Court judged it breached certain contractual terms.
Eircell said its volume discount agreement with Meridian will be terminated immediately further to an earlier High Court judgment.