Telefónica Ireland said service revenue fell to €177.8 million in the first quarter of 2011 compared to €196.2 million in last year's first quarter. Contract customers at its O2 mobile network increased by 5 per cent, or 34,200. However, O2's mobile customer base was down on a quarterly basis, totalling 1.68 million at the end of March compared to 1.696 million in the last quarter. Monthly blended average revenue per user fell €2.21.