New figures from ComReg show that the average mobile phone user used 4.8GB of data a month during the fourth quarter of last year, a massive jump of 52.3% on the same time the previous year.
ComReg's latest quarterly report on the electronics communications market also showed that the number of text messages sent declined by 10.7% to 83 texts a month.
The report also showed that the estimated household broadband penetration rate - both fixed and mobile - was 88%. This was higher than the euro zone average of 85%.
It also revealed that fixed broadband subscriptions rose by 3% to 1.401 million compared to the fourth quarter of 2016.
Meanwhile, average broadband speeds continued to increase in the last three months of 2017.
ComReg said that about 84.3% of all fixed broadband subscriptions were equal to or greater than 10Mbps, up from 79.8% in the fourth quarter of 2016.
It noted that mobile minutes form the majority of voice minutes at 77.9%, with fixed line minutes making up the remaining 22.1%.
Mobile voice minutes rose by 1.8% while fixed voice minutes fell by 0.8%, the ComReg report added.