The number of people using O2 Ireland mobiles grew by 6,000 over the second three months of the year to 1.599 million.
In a statement today the company also said that service revenue grew by 3.3 per cent compared with the same period the previous year.
The average revenue per user, an indication of what O2 earns from each customer, increased by one euro to €46.
The company also reported a 9.8 per cent rise in the number of text messages sent, with 392 million texts send between April and June.