AT&T today announced their quarterly earnings. As expected, the nation’s second largest carrier remained the leader in iPhone sales in the U.S.

For the second quarter of 2012, AT&T activated 4.3 million new iPhones, or 78 percent of all smartphone sales. In the first quarter of 2011, AT&T activated 3.6 million iPhones. This means AT&T’s iPhone sales were nearly 19 percent better year-over-year.

iPhone Sales

iPhone Sales

In total, the company announced they added 726,000 net subscribers for a total subscriber count of 103.9 million, up from 103.2 million in the December quarter.

Last week, Verizon reported iPhone sales of 3.2 million.

Of note, Apple will release its latest quarter results later today after the markets close.

(Graphic: iPhone sales by 9to5Mac)