"All of that is supportable," says Jim Hull, vice president of engineering services, because end-to-end reliability and performance have improved to the point where the Internet is now "good enough."

MasterCard isn't the only organization to take notice. "The Internet is improving in its performance and in its price point," says Doug Hill, associate technical fellow and network chief architect at The Boeing Co. in Chicago. "We're using it a lot more than we used to."

In addition to supporting smaller remote offices, Boeing even runs some voice-over-IP traffic over the Internet, although broader adoption will need to wait for quality-of-service (QoS) functions to evolve, Hill says.

By using the Internet, both companies cut operating costs because the traffic no longer moves over ISDN, leased lines or other private network services.

"Enterprises are increasingly interested in Internet substitution. They're finding that they can offload a great deal of [network traffic]," says David Passmore, an analyst at Burton Group in Midvale, Utah.