It actually means Integrated Services Digital Network, and refers to telephone networks which use digital, rather than audio signals. But its long and slow gestation has led to the jests. More seriously, others suggest that ISDN has taken so long to implement that it should be abandoned in favor of newer and faster technologies.
With industry-wide standards finally in place, or nearly so, however, ISDN is finally ready to take off, a panel of computer and telecommunications executives said.
Because ISDN systems do not need to convert digital information to sound, and the switches work at very high speed, data can be transferred across ISDN networks at speeds ranging from 64 kilobits per second to 1.5 megabits per second, far faster than regular modems.
Gary Handler, an executive with Bellcore, noted that the number of ISDN switches in operation on American telephone switches has risen from 100 to 2,500, and the number of customers from less than 100,000 to about 300,000 since 1992.
Johnson said the cost of the computer cards required for ISDN has started to drop below $500, compared with more than $1,500 in 1992.
And Dave Dorman, chief executive officer of Pacific Bell, said his company will spend $16 billion over the next decade to convert its telephone networks to digital system.
New computer applications are among the forces driving ISDN in North America.
Business is increasingly turning to video-conferencing and new whiteboard software, said Intel President Andy Grove, whose company announced an ISDN chip in 1986. Intel's Pro Share software, some versions of which are bundled with ISDN cards, permits users in widely dispersed locations to hook their computers together and share data and applications in real time. Some versions will also transmit video and audio signals over the same communications line.
Although such systems can cost more than the computers they run on, they can substantially reduce business travel and permit faster and better-informed decisions.
Handler cited other ISDN advantages. ISDN devices answer calls much faster than conventional telephone switches, reducing the time to connect a call to less than a second. That can cut the time required to complete data transactions to a fifteenth of the time which conventional systems take.
Group IV fax, which runs over ISDN, is four to six times as fast as conventional fax and produces higher quality. Medical facilities can use ISDN to transmit X-rays and other diagnostic information, improving health care services while reducing costs.
And on the consumer front, a three-store deli chain which linked its stores via ISDN was able to reduce the lead time for large orders from 24 hours to one hour, a move which led to a dramatic increase in business.
John Seazholtz, vice president of technology for Bell Atlantic, cited the case of an inner city school in Union City, N.J., in which seventh grade students and their teachers were given computers linked via ISDN connections to their school. The dropout rate plummeted from 50 percent to two percent, achievement scores soared, and teachers have elected to implement year-round schooling, in which students will receive assignments they can complete at home during the regular vacation season.
That proves a point made by Microsoft's Mike Maples, worldwide products group vice-president. Computer users are beginning to view their computers less as replacements for calculators and typewriters and more as communications tools, he said.
"ISDN is open, fast and digital. And ISDN is here now," said Maples, who uses an ISDN connection between his home and office every day. Maples called the ability to connect to his office network over a telephone company line, and to work nearly as fast as he can in the office, a "killer app" for ISDN.
Most of Microsoft's senior executives have ISDN connections, and Microsoft's interest has helped push the telephone company which serves its Redmond, Washington campus into widespread availability of ISDN.
But consumers may push ISDN much faster than business has done so far, Maples said.
The use of Mosaic, a Windows-like interface for browsing the Internet, has exploded since the product came out in mid-1993. Mosaic, which can access not only text, but graphics, sound, video and other high-volume data, requires fast, high quality network connections using the TCP/IP network protocol, the main protocol of the Internet. Use of that protocol will increase dramatically with the release of Windows 95, which includes TCP/IP.
Maples didn't mention it, but IBM's latest version of OS/2 already includes not only TCP/IP, but a built-in Internet dial-up access service and a Mosaic browser.
Robert Metcalfe, developer of the widely used Ethernet networking technology and panel moderator, wondered whether ISDN could only be considered an interim technology, to be overtaken by even newer and faster standards such as asynchronous transfer mode.
"In the computer industry, nothing is forever," responded Handler, noting that consumers and businesses spend billions of dollars on technology destined to be overtaken by newer and better systems only a few years later.
Jibed Grove: "It's interim like Ethernet was interim 10 years ago."
