EXCELSIOR SPRINGS, Mo.—Telecom contractor Bob Sellenriek recently bought three massive bulldozers and fitted them with cable-burying plows that had been gathering dust in his warehouse for a decade.

Amid a new building boom for fiber cable, some companies are wary of the collapse of 2001, which took out millions in stock-market value,

Mr. Sellenriek needed the plows for something he has done very little of since the telecom bubble burst and wiped out $2 trillion in stock market wealth more than 10 years ago: laying miles of new fiber-optic cable. After years of licking its wounds, and with much of the fiber-optic cable capacity in the ground still unused, the telecom industry is going on another building spree.

Some 19 million miles of optical fiber were installed in the U.S. last year, the most since the boom year of 2000, research firm CRU Group says. Corning Inc., a leading maker of fiber, sold record volumes last year and is telling new customers that it can't guarantee their orders will be filled.

RWF Bron, a Canadian maker of the specialized "cable plows" used to bury fiber-optic cable, says the last six months were its busiest in a decade. And railway Norfolk Southern Corp. says it is finally seeing interest in the empty plastic pipes it buried along its tracks in the late 1990s, betting telecom companies would pay to string fiber through them.

It is early days in what some in the fiber-optic business are calling a new boom for their long-beaten-down industry. Demand is being driven by skyrocketing Internet video traffic, requests from the financial sector for ever-faster trading connections, and soaring mobile phone use—which has to be tied into landline networks. Even the 2009 economic stimulus plan, which set aside $7.2 billion for telecom projects, is pitching in.

Cisco Systems Inc. predicts that mobile data traffic will nearly double every year through 2015. But Andrew M. Odlyzko, a University of Minnesota math professor who warned a decade ago about slower-than-expected Internet growth, says predictions of skyrocketing mobile traffic seem overly optimistic: Mobile bandwidth may be too expensive to increase, he says. Every cellphone data connection generally runs from a phone company's cellphone tower into a landline telecom network.