AT&T reported a 24 percent fall in fourth quarter earnings despite strong wireless sales, due to high costs of supporting Apple's popular iPhone 3G. 
The top U.S. phone company earned $2.40 billion in the last three months of 2008. That was down from $3.14 billion a year earlier.
AT&T added 2.1 million wireless subscribers, ending the quarter with 77 million subscribers.
The major draw for customers was Apple's iPhone 3G, for which AT&T is the exclusive U.S. carrier. It added 1.9 million iPhone subscribers in the quarter, down from 2.4 million in the third quarter, when the latest iPhone model was released. Around 40 percent of those signing up for the iPhone were new to AT&T.
AT&T pays hundreds of dollars in subsidies for the right to be the sole U.S. carrier for the iPhone. The company has said the iPhone subsides are worthwhile as the popular phone attracts new, higher-spending customers. It aims to make that money back in service fees over the two-year contract attached to each phone.
