The popularity of smartphones has driven customers at O2 Ireland, with the number using the devices rising by 40 per cent in the year to the end of June.
The company, which is owned by Telefónica, said its postpay customer base increased by 12,000 in the six months, and by 29,000 over a 12-month period.
O2's mobile broadband customer base also rose, gaining 20,000 over the year to 165,600.
The telecoms operator said mobile data revenue now represents 40 per cent of total mobile service revenues, growing by 11.8 per cent year-on-year.
Total service revenue for the fist half of the year was €352 million, lower than the €389 million recorded in the same period a year earlier. O2 blamed the decline on better value for money products and cuts in the mobile termination rates charged to other operators to carry calls on its network.
Monthly average blended ARPU was down slightly to €34.0 in the second quarter, and €34.2 for the six months, down from €37.1 for the same period last year.
O2's fixed line business customer base grew by 7,300 for the first six months of 2011, bringing the total to almost 20,000 customers.
The operator's total customer base was 1.687 million at the end of June 2011, down 8,200 in the second quarter.
Its move into financial services has seen some success, with 40,000 customers signing up to the O2 Money Card since it launched in February.
"From a macro perspective, economic conditions remain extremely challenging, with consumer sentiment taking longer than expected to recover," Telefónica Ireland chief financial officer Paul Whelan said.
"In response we continue to innovate and extend our range of price plans, focusing on the value and flexibility that we know our customers want."
The Telefónica group posted a 16.3 per cent decline in first half profit today, stung by weakness in its Spanish home business and one-off charges related to the impact of the economic downturn.
However its telecoms operations in Latin America continued to perform strongly, powered by lucrative smartphone growth which allowed the group to offset weaker growth in more mature markets.
Group revenues rose 6.3 per cent overall, although in Spain alone they were down 6.1 per cent, below analyst expectations.
Net profit stood at €3.16 billion.
Underpinning Telefónica's performance was an 18.4 per cent rise in Latin American revenues, and chairman Cesar Alierta predicted that Brazil alone would soon become the group's main revenue driver.
Additional reporting: Reuters
