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ISDN replaces "sneakernet," 4 phone lines.

Last year, the people in Carmen Moore's department had to take over a fellow employee's PC anytime they needed to use a Postscript-capable printer.

Now the staff at the U.S. General Services Administration office in Atlanta can send their print jobs to John Penman's printer without forcing him to quit his own work.

They use ISDN's D channel to share the printer, while dedicating the two B channels to voice. Bottom line: they're replacing four phone lines with each basic rate ISDN line.

Moore, supervisory computer specialist, says before ISDN the only way her staff could use the printer they wanted was via "Sneakernet,"--walking a disk over to fellow worker Penman's office and tying up his PC while the printer completed their jobs.

The single 16 kb/s D channel is shared by two PCs with terminal adapters. Staffers send to Penman's printer and he hears only an audible tone on his telephone set, then the whir of the printer. He no longer needs to give up access to his desktop PC.

GSA, in downtown Atlanta, gets its ISDN through Southern Bell's ESSX centrex service. The building is served by a DMS-100 central office switch.

Moore downplays the glamor of the application, but not its effectiveness.

"This is nothing great and wonderful, but it works for us and it definitely met a need that we had. Everybody wants a laser printer on their desk, but that's too expensive," Moore says. "We started looking at printer sharing. It turned out even better than we thought."

Each PC in Moore's department had an internal modem and a separate phone line used for cc: Mail messaging and for remote systems support for users in the field.

"In effect, we each had two different phone lines, for voice and for the modem. With ISDN, one line has taken the place of four."

Moore and the branch chief, for example, use one ISDN line. Each uses one B channel for voice and they share the D channel to access printers and a modem pool.

Cost not an obstacle

The cost of terminal adapters, often an obstacle to user acceptance of ISDN, was not an issue, explains Tom Rawlings, supervisory computer specialist.

"I did a cost comparison," says Rawlings. "If you take an (ISDN) terminal and compare it to a typical phone with a 9600 baud modem and two phone lines, it comes out within less than $100 difference."

That difference is quickly overcome with the line cost savings. Also, as Communications Manager Randy Gray notes, most people in the office had internal 2400 baud modems. Now they all have access to the 9600 modems in the pool.

"It seems that 9600 baud in ISDN is faster, too," says Rawlings. "We did some testing with the ISDN gateway into the cc:Mail post office. It rings, answers and it's done. A 9600 baud modem normally takes 15 to 20 seconds just to sync up."

Rawlings looks at ISDN from an applications evaluation standpoint for the agencies GSA serves.

"We try to think up new things to use it for," he says. "It is difficult to go out and sell something to another agency if you don't know how to use it yourself. That is what we are trying to do, learn how to use it."

For him, cost savings are only one appeal of ISDN.

"Modems at best are not really a fantastically dependable piece of equipment," he says. "This is much more reliable."

Video pilot project

GSA is also running an ISDN video-conferencing pilot project, connecting Atlanta with offices in Washington and Chicago.

Randy Gray and Paul Morris manage that test. Initially they used two B channels rate-adapted for 56 kb/s each over Sprint's portion of the federal FTS-2000 network. They are now testing it on AT&T's portion of the network.

The 112 kb/s rate provides satisfactory video quality, Gray says, especially since the conferencing is designed for small groups and they use proprietary algorithms. The project involves a mobile Sony system.

For the pilot project, GSA brings in representatives of other agencies for sample videoconferences. The regional GSA administrator also uses the equipment for full-fledged conferences.

Other potential uses of ISDN include access to X.25 packet-switched services across the FTS-2000 network and a connection to a Honeywell mainframe.

"We service a number of other agencies, so we would like to use our office as a demonstration area to show the other agencies what they can do with ISDN. There may be a lot of others out there who have the same needs," explains Moore.

"We are also working with Southern Bell on using electronic data interchange for billing over ISDN. We hope to have that system up and running by the end of this fiscal year."
COPYRIGHT 1992 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Integrated Services Digital Network; General Services Administration
Author:Tanzillo, Kevin
Publication:Communications News
Date:Aug 1, 1992
Words:798
Previous Article:Plan for the expected, prepare for the unexpected.
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