The market was unimpressed as all those who had never heard of the man when AT&T Corp announced that its board had elected John Walter, chairman of printer R R Donnelley & Sons, as its new president, chief operating officer and heir apparent to chairman Robert Allen. He was chosen because He’s transformed a large, old-line company challenged by new technologies and changing markets into a tough global competitor and meeting those challenges is what leading the new AT&T is all about, Allen said. He said that, starting in January 1998, he and Walter will split the duties of chairman and chief executive, with Walter taking both posts later.