Lucent Technologies Inc. and Nortel Networks Ltd., two of the leading suppliers of telecom network infrastructure, could be most threatened by the move to Linux. Those vendors, using proprietary technology and software, supply much of the central-office switching systems and operational-support systems used by most of the large U.S. phone companies. Neither company is a member of OSDL.

Lucent is evaluating several vendor offerings of CGL and is prototyping products internally, but hasn't officially revealed any products based on carrier-grade Linux. Nortel has been developing its own version of CGL and already is shipping a number of products using that operating system. It's the de facto standard for all new Nortel product development, but "it will be a number of years before it is commonplace," says Rich Wilkie, Nortel's services edge chief architect.

"There are a lot of compelling reasons why it makes sense to use CGL as a base for a lot of different telecom products," says Howard Trickey, director of the systems software research department at Bell Labs. "But there are places where it doesn't make sense." The Linux kernel is larger than some "old-school" operating systems, which may make it inappropriate for some applications where a small memory image is desired. And Linux is still maturing in terms of providing real-time control, which is important for some telecom applications.

Carriers may not care whether their vendors build products using CGL, Trickey and Wilkie say. What they really care about is whether their equipment vendors can ensure that their products meet the reliability and availability standards carriers require. Several leading telecom carriers declined to comment on this topic, saying only that they were monitoring CGL developments and that they would rely on their equipment suppliers to use the best software for the job.

Linux will slowly replace proprietary operating systems in telecom equipment as carriers replace old equipment with new technology, Wilkie predicts.

"The old will simply go away and it will be hidden from the user," he says. "So the speed at which you evolve to a new OS is driven by the engineering team building the product and not by the user community. The users just want to use the box as it came."

Carriers, however, take a long time to introduce new products into their networks, says Julie Giera, a VP at Forrester Research. "It is inevitable, but it will be awhile before carrier-grade Linux is introduced and begins to be stressed by the telecom carriers," she says. "The introduction of a new technology platform is always exciting, but carriers will be concerned about the cost of maintaining the code and integrating all of the individual pieces and parts together. Enhancing Linux to make it reliable enough for carriers will make it a much bigger monster to feed and care for."

It also, over time, will provide benefits for businesses. Those involved in the CGL effort are quick to say that all new features and improvements eventually will appear in the Linux kernel used for servers, desktops, and other systems. That means business-technology managers using Linux can look forward to carrier-grade availability and reliability in their own data centers.