Eircom has lost about 27,000 customers in the three months to the end of March 2004, a new survey by the telecoms regulator shows.
The latest market review by the Commission for Communications Regulation (ComReg) found that 252,000 customers have now signed up with rival telecoms operators, a 12 per cent increase on the previous quarter.
The customer defections occurred during a quarter when Eircom increased its line rental for the third time in 12 months, provoking consumer outrage.
It is the second successive quarter that Eircom has lost large numbers of its customers to rival firms such as Esat BT, Smart Telecom and MCI. In the three months to the end of December 2003 it lost 20,000 customers, as people signed up with rivals using carrier pre-select systems.
These systems enable businesses and consumers to switch operators for the call portion of their telephone bill.
But they must still pay their rental charge to Eircom via a separate bill.
A new single-billing system, which enables Eircom's rivals to offer their customers line rental as well as call services, is due to be available shortly.
It is predicted this will make it more attractive for customers to use alternative telephone suppliers.
Rival firms now hold 14 per cent of all customer telephone lines in the Republic, according to the review. Mr David McRedmond, Eircom's commercial director, said the customer losses reflected increased competition in what is now one of the most liberalised markets in Europe.
Consumer complaints made to ComReg about fixed-line operators increased by 34 per cent in the first quarter, compared with the previous three-month period.
There were 379 consumer complaints made, compared to 282 in the fourth quarter of 2003.
The number of complaints made about mobile phone operators and broadcasting firms fell by 45 per cent and 46 per cent respectively.
The report shows that mobile phone penetration is now at 88 per cent of the population, with about 3.5 million handsets in use.
About 122,000 mobile phone users have changed operator and kept the same mobile number since the introduction of mobile number portability in July.
Despite the introduction of this system, there was little movement in the overall market share held by the three mobile firms.
Vodafone's market share stands at 54 per cent, O2 is at 40 per cent and Meteor holds 6 per cent.
Irish mobile phone subscribers sent 910 million text messages during the first quarter.
Total revenues generated by the firms operating in the communications market now stand at €3.57 billion on an annualised basis, an increase of 3 per cent increase since 2003.
