In his latest book, “The New Market Leaders,” Fred Wiersema sketches out a profile of the companies that will lead their industries in the next decade — including several telecom outfits. Wiersema believes the new leaders will be the most focused companies, not simply the biggest. We talked with him about which companies will emerge from economic slowdown and lead telecom into the next decade.

On how his model is enduring the downturn: “It's very reassuring how well it has held up. The companies that are performing well have momentum built into their products. In bad times, that helps them through the bumps. Have we seen some real bloodbaths? Certainly. But the bloodbaths are traceable.”

On the current telecom environment: “A lot of people placed a bet on the growth of our field, and they failed. It doesn't mean the business is wrong; it means the bet was wrong. That's what you saw with Cisco. Year-over-year sales growth has continued to increase 18%. That's a pretty stellar number. AT&T Wireless is up 40%. We hear all this gloom and doom about the industry caving in, and if you look at these companies, they've all got double-digit growth, which is something most companies would die for.”

On being all things to all customers: “The one thing that I'm seeing is the one thing that sets them apart: Leaders are very focused. In these tough days, they find it easier to focus on the two or three things that make a difference. You don't have to break up the company, but you have to make sure that your business units are focused. Why is GE able to do what AT&T is not? At GE they have a dozen businesses that are sharply focused on what they do. Each one of them runs as a separate entity. It comes down to focus on the individual business level. That was the original idea behind the breakup of AT&T, when they spun off Lucent. The real primary thing was that each one of those businesses had a different strength.”

On size: “There really is no minimum size that you have to be to become a leader. Look at a company like a Sycamore that really came out of nowhere — or JDS Uniphase or Broadcom. These were not particularly big companies. The essential question is: Can you really do better than people that are about your same size?”

DOSSIER FRED WIERSEMA

Occupation: Diamond Fellow and founder of the Center for Market Leadership at DiamondCluster, a business strategy and technology solutions firm

Place of residence: Boston

Current reading: “Guns, Germs and Steel: The Fate of Human Societies” by Jared Diamond; “The Tipping Point: How Little Things Can Make a Big Difference” by Malcolm Gladwell

Favorite Web site: (besides his own, www.wiersema.com): “I go to so many of them, but the one that is most useful to me is my Yahoo site.”

Next project: Promoting the book and making sure it gets into the right hands