AT&T Inc., the country’s largest wireless carrier, is testing a technology that can improve the signal available to cell phones in subscribers’ homes, and plans to make it available in a trial market next year.  John Stankey, chief executive of AT&T’s Operations division, said Tuesday that the company is testing so-called “femtocells” in employees’ homes, and is looking at a broader, city-sized test with customers in the second quarter. Read More →