ADTRAN Announces ISDN Product Enhancements.

HUNTSVILLE, Ala.--(BUSINESS WIRE)--March 10, 1997--ADTRAN, Inc. (Nasdaq: ADTN), a leading supplier of voice and data communications network access devices, introduced its latest ISDN product enhancements today.

"ADTRAN has been designing, developing and manufacturing ISDN equipment for almost a decade," ADTRAN ISDN Product Manager Bill Moon said. "We've been adding to a solid product line that, today, addresses everything from a simple set-up process for those using ISDN at home, to the high-end user in corporate networks."

ISU 512 Now Equipped with an S/T Interface

The ISU 512 is an ISDN inverse multiplexer combining the bandwidth of four Basic Rate ISDN lines into one powerful network connection that offers up to 512 kbps data transfer. The ISU 512 is primarily designed for video conferencing and disaster recovery. When used in a disaster recovery application, the ISU 512 offers a powerful 512 kbps data pipe for data backup. The ISU 512 with an S/T interface is an addition to the already successful ISU 512 with a U interface. The new ISU 512 S/T provides a very cost-effective solution for connecting the ISU 512 to devices with an S/T interface such as a PBX.

Macintosh GUI Added to Express Configuration Wizard

The ADTRAN Express XR/XRT ISDN modems are now equipped with an Express Macintosh Wizard. The Express Macintosh Wizard is a Graphical User Interface, or GUI, designed specifically for the Macintosh user. The Express Macintosh Wizard offers an attractive, simple way to examine or configure the Express XR and XRT ISDN modems. Prior to the addition of the Express Macintosh Configuration Wizard, configuration of these products when used with a Macintosh computer was accomplished using a virtual terminal program.

These modems also feature Expert ISDN, ADTRAN's patent-pending technology that automatically detects phone company parameters, namely SPIDs and Switch Type. Users simply enter their ISDN phone numbers and this sophisticated software provides the information necessary for ISDN service setup. This innovation, coupled with the Express Macintosh Configuration Wizard, makes using ISDN fast and easy.

To maximize data transmission, these units support Stac" LZS(TM) compression in accordance with the PPP standard and are compatible with Ascend(R) compression techniques. Remote configuration and extensive diagnostic capabilities allow the unit to be configured and maintained from a centralized location without the need for on-site support.

The Express ISDN modem is available in two models: the Express XR, a data-only device, and the Express XRT, which supports up to two analog devices such as a telephone, FAX machine, or analog modem. When transmitting data at maximum throughput over both B channels using multilink PPP, the Express XRT automatically detects calls on the analog ports and adjusts the data transmission speed to 64,000 bps by limiting data transmission to one B channel and accepts the analog/voice call on the other B channel. When the voice call is completed, the Express XRT automatically resumes data transfer over both channels.

The Express XRT also features a patent-pending technique that permits using an existing analog modem without requiring an additional COM port on the computer. The Express XRT automatically determines if a call is received from an analog modem or ISDN device and adapts transparently. The Express XR and XRT are ideal for Internet access, remote access, and home office applications.

ADTRAN Corporate Overview

ADTRAN was established in 1985 to design, develop and manufacture advanced transmission products for high-speed digital communications. Today ADTRAN is a primary provider of DDS, ISDN, T1/FT1 and HDSL digital loop products to Regional Bell Operating Companies and many well-known OEMs. The broad selection of customer premises products offered by ADTRAN includes a complete line of DSU/CSUs, a variety of ISDN extension and network terminating products and flexible T1 multiplexers. For more information regarding ADTRAN and its products, call 1-800-326-3700, fax [phone] or E-mail: [e-mail].

CONTACT: ADTRAN

Stacy Thomas, 205/971-8488, [e-mail]

Bill Moon, 205/971-8456, [e-mail]