Strong growth in mobile data contributed to a first quarter growth in profit for AT&T, the second largest operator in the US.

Overall net income in the first quarter increased to $3.7 billion, up 3.2 per cent from $3.6 billion in the same quarter in 2012.

Wireless data revenue rose by 21 per cent to $5.1 billion, while total wireless revenues increased by 3.4 per cent to $16.7 billion.  Operating margins in wireless services increased to 43.2 per cent.

However, the operator’s lanline business dragged down overall revenue, which fell by 1.5 per cent to $31.4 billion, a performance which was below analyst estimates.

Brighter news came from the wireless side where AT&T sold a record 6 million smartphones in the quarter, including 4.8 million iPhones. It also said LTE rollout was beating its schedule and now had coverage of 200 million people.

Randall Stephenson (pictured), AT&T chairman and CEO, described the wireless network performance as “terrific”.

The operator gained more contract customers than analysts expected in the first quarter. It added 296,000 net additions in the period. However, its performance was still way behind market leader Verizon Wireless which added 677,000.

AT&T suffered a net loss of 184,000 prepaid subscribers. And its resale business reported a loss of 252,000 due to “resellers’ rationalisation of their low or no usage accounts”.