Eircom has said its revenue for the quarter ended September 30 was down to €313m, or by €10m (3%) on the corresponding quarter last year.
Operating costs were €199m, down €3m, which was a 2% improvement.
The group said a fall-off in its fixed line business had off-set gains it made in the mobile market. Mobile revenue for the three month period rose by 2%.
Earnings before tax fell by 6% to €114m as a result of planned investment in subscriber growth.
CEO of eircom group Richard Moat said: "The rate of revenue decline has slowed significantly, an encouraging sign of stabilisation, helped by two consecutive quarters of mobile revenue growth.
"Our bottom line performance remains in line with expectations, following a decision to make commercial investments this quarter that will deliver long term growth."
Eircom's new fibre network now supplies one million premises, and the company said it is on target to increase that to 1.6 million by June. The network can support broadband speeds of up to 100Mb per second.