AT&T and Nokia each announced severe belt-tightening measures this week, but each laid out different approaches to address market share issues. Suffering from the loss of landline subscribers, AT&T announced Thursday that it will cut its employment base by 4%, or 12,000 employees. The company, however, said it plans to increase staff in broadband, wireless, and video. AT&T has been riding its exclusive deal with Apple’s iPhone, and the telecom company expects to gain market share in the mobile phone category next year. At its annual Capital Markets Day, this year in Brooklyn, N.