CCITT COMMITTEE MEMBERS CALL FOR STANDARDIZED APPROACH
Challenge Vendor For Co-Opting 28.8 Kbps Standard

SKOKIE, Ill., -- June 8, 1992 --Two members of the Consultative Committee
on International Telephony and Telegraphy (CCITT) have challenged the
recent introduction of a modem by Motorola Codex that Motorola Codex
claims conforms to the developing CCITT standard for 28.8 Kbps dial-up
communication.

The standard is known in its working form as "V.Fast," a nickname Motorola
Codex borrowed for its 326XFAST modem. But with the CCITT study group at
least a year from agreeing on a standard, and the standard itself not
expected to be officially adopted until 1994, any claims of conformance
are dubious, according to the committee members.

"Most of the fundamental things haven't even been agreed on yet," said Dick
Stuart, chairman of the CCITT committee developing the 28.8 Kbps standard
and technology vice president of Penril Datacomm Networks, Gaithersburg,
Md. "I've had people suggest to me that we change the preliminary name for
the standard (V.Fast) just because of what has happened. Some people have
even asked me if we can have a number assigned to the standard, whereas
normally that's one of the last things we do."

Dale Walsh, vice president for advanced development at U.S. Robotics, Inc.,
says the Motorola Codex modem incorporates some early proposals that the
company made to the CCITT committee. "But it doesn't conform to the
standard we are working on," Walsh said. "Nobody can make that claim
yet."

Stuart said that Motorola Codex's move creates confusion for customers and
could delay work on the standard.

"Now it becomes more of an issue of turf protection for the committee,
rather than trying to get the best recommendation for all concerned," he
said. "It' s tough for a body to come to an agreement when maybe what
they'd be agreeing on has already been done by one manufacturer."

Jonathan Zakin, executive vice president of sales and marketing at U.S.
Robotics, noted that while Motorola Codex promises an upgrade path when
the 28.8 Kbps dial-up standard is adopted, USR is the only firm offering a
field upgrade. The company will offer users the opportunity to purchase an
easily installed daughterboard that will plug in to existing USR modems,
thus allowing an upgrade to the CCITT standard when it is finalized.

"Nobody knows what the standard for '28.8' will be, but we do know what the
maximum hardware upgrade will be," said Zakin. "So while we won't say that
our modems conform to the 28.8 standard, we can say that our modular
architecture provides a clear upgrade path to whatever that standard will
be. And it's something a user can install in 10 minutes -- which means
they won't be without their modem while it's at some factory being
upgraded."
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CCITT 28.8 Kbps STANDARD: BACKGROUNDER

SKOKIE, Ill., -- June 8, 1992 --The standard for 28.8 Kbps dial-up
communications being developed by the CCITT will stretch the limits of
dial-up telephone lines. But don't expect to be sending files at top
speeds immediately.

Dale Walsh, vice president for advanced development at U.S. Robotics, Inc.,
cautions that most users won't be able to achieve the maximum speeds
permitted under the standard right away. When the standard is adopted,
modems that conform should be able to transmit at 19.2 Kbps on lines where
a modem conforming to V.3bis (the current high-speed standard) can now
transmit at 14.4 Kbps. But Walsh, a member of the CCITT committee
developing the standard, says it is being formulated with the increasing
digitization of dial-up phone networks in mind.

"The improved quality of phone lines, as much as any modem technology
improvements, has made high-speed dial-up communications possible," says
Walsh. "We are designing the standard keeping in mind that phone networks
will use more and more digital circuits and digital central office
switches."

Consequently, speeds in the neighborhood of 28.8 Kbps will be the
exception, rather than the rule --at least until the public switched
telephone network becomes completely digital.

"I'd say that when it's finished in a year or so, the standard will allow
19.2 Kbps transmissions on about 80 percent of all lines, 24 Kbps on 50
percent of all lines, and 28.8 Kbps communications on 20 percent of all
lines," says Walsh, who also helped develop the CCITT V.32bis standard for
14.4 Kbps dial-up communications. "As the phone networks improve, top
speeds will be more easily achieved, so I think it's more realistic to
think of it as a 19.2 Kbps standard that is sometimes capable of higher
speeds."

A common misconception is that the coming 28.8 Kbps standard will allow
speeds of 115.2 Kbps, when combined with V.42bis data compression. Walsh
noted that such calculations are based on an assumption that V.42bis
allows 4-to-1 data compression. Outside the lab, V.4bis allows compression
ratios between 2-to-1 and 3-to-1 meaning that under real-life conditions,
the forthcoming standard will allow maximum throughput of about 86.4
Kbps.

"It's a mistake to use the 28.8 number and max everything out from that,"
said Walsh.

Not that the 28.8Kbps standard doesn't have its advantages. After all, 19.2
Kbps is an improvement over 14.4 Kbps. And the forthcoming standard will
adjust for line conditions -- a critical factor in high-speed data
communications -- like no previous standard. The standard under
development will include a "probing" function that the modem can use to
"sound out" the quality of the phone line. That will allow the modem to
optimize transmissions to take advantage of available bandwidth.

"We are still working on the training sequences," says Walsh. "But before
transmission starts, the standard will enable the modem to determine what
bandwidth is available and how to best position the signal to match
available bandwidth."

The standard achieves higher speeds through its ability to use more of a
line' s bandwidth -- not just the center portion of the channel used under
current standards.

"It will more closely match the modulation scheme to what's available,"
says Walsh. "That way, the modem can shape the transmission to adapt
precisely to the channel -- which is very important if you want to
transmit at high speeds."

The most recent committee meeting was held last week. Still to be agreed
upon are such critical issues as training sequences, coding schemes and
signaling rates. Walsh said he expects the committee to reach final
agreement in 1993, with official CCITT adoption likely in 1994.

While some have taken to calling the standard under development V.Last,
Walsh isn't convinced this will be the final modem standard. After all, he
notes, no one thought dial-up phone lines would ever be this noise-free,
and further advances in that area could make even higher speed dialup
communication possible.

"I'm certain we'll have at least a fax version of this standard as the
quality of phone lines keep improving," he said. "We're trying to be sure
that this standard will serve users into the year 2000. But modem
standards are like wars -- you always think it's going to be the last
one."

U. S. Robotics, Inc., (NASDAQ: USRX) is a worldwide designer, manufacturer
and marketer of data communications hardware and software. U.S. Robotics'
product lines include Shared Access resource-sharing products for remote
LAN access, the Total Control modem management system and network access
servers for central data sites, BLAST software products for terminal
emulation, file transfer and remote control, Courier data and fax/data
modems for corporate users, WorldPort portable data and fax/data modems
for traveling professionals, and Sportster data and fax/data modems for
small business, home office and entry-level users. Both corporate
headquarters and manufacturing operations are based in Skokie, Ill. U.S.
Robotics owns and operates Miracom Technology Ltd., Slough, England and
U.S. Robotics, s.a., Lille, France. The company markets its products to
business, industry, government agencies and original equipment
manufacturers.

U.S. Robotics, 8100 North McCormick Blvd, Skokie, IL 60076
708-982-5010   800-DIAL-USR

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