Interesting interpretation of the word "lost" you've got there. Right in the headline of the article you linked to it says "AT&T lost $3.9 billion in Q4 2012, earned $7.3 billion profit for the year".
But I suppose you could be referring to $7.3 billion profit for the year as 3+ billion per quarter if you're bad at dividing by four.
Nevertheless, according to page 30 of AT&T's annual report http://www.att.com/Investor/ATT_Annual/2012/downloads/ar2012_annual_report.pdf the dollar amounts (in millions of dollars) for "Construction and capital expenditures" for the past few years are:
So 17-20 billion dollars per year in construction and capital improvements. If you've got evidence to show that AT&T is NOT investing tens of billions of dollars per year in improving the network you should maybe contact the SEC or FCC. Otherwise, it's not really polite to imply that AT&T isn't investing in infrastructure without evidence to support your claims.
Disclaimer: I work for AT&T but not in wireless or in finance. But I'm well aware of AT&T's public communications of how much the company is investing.