ADTRAN Introduces Compact ISDN Channel Bank for Use with T1 Carrier Systems; Industry's First Bank to Provide Service For up to 10 ISDN Lines.

DALLAS--(BUSINESS WIRE)--June 25, 1996--ADTRAN, Inc. (NASDAQ:ADTN) introduced today the BR1/10, the industry's first ISDN channel bank that can deliver 10 Basic Rate ISDN lines over a single T1 line.

The announcement was made at the SUPERCOMM trade show in Dallas.

"Not all customers utilizing Basic Rate ISDN, or BRI, are served from a central office with ISDN capabilities. BRI service can be delivered over a T1 line from an ISDN upgraded office to a non-ISDN central office and then extended to the customer. The BR1/10 represents a miniature, cost-effective way to accomplish just that," ADTRAN ISDN Telco Product Manager Wayne Cranford said.

A T1 line offers 24 channels for providing digital or analog services. Traditionally, one ISDN line requires 3 of these channels: two utilizing the full bandwidth of two channels, and one utilizing only a fourth of the bandwidth available from a third channel for call set up information. The BR1/10 can be provisioned to maximize all 24 channels by multiplexing or combining four of the third channel bandwidth requirements onto one of the channels. This gives service providers the ability to deliver two additional ISDN lines, for a cost effective method of delivering a total of ten ISDN lines using one T1 line.

The BR1/10 system consists of a shelf, three common cards, and up to ten individual U-BR1TE cards specifically designed for this system. The U-BR1TE provides the industry standard Basic Rate ISDN interface for the customer's network termination equipment, and is compatible with current ADTRAN U-BR1TES. The Single 19-inch BR1/10 shelf accommodates one BR1/10 system and mounts in either a 19-inch or 23-inch relay rack. A Dual 23-inch BR1/10 shelf accommodates two separate BR1/10 channel bank systems, for up to 20 BR1 lines. Both shelves are 11 inches deep and 2.875 inches high. A 23-inch shelf (2x or 2-by) accommodates two separate BR1/10 channel banks, for a maximum deployment of up to 20 U-BR1TE circuits. Both shelves are 11 inches deep and 2.875 inches high for a compact modular channel bank.

ADTRAN was established in 1985 to design, develop and manufacture advanced transmission products for high-speed digital communications. ADTRAN is a primary provider of DDS, ISDN 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]. ADTRAN can be found on the Internet at www.adtran.com.

CONTACT: ADTRAN, Huntsville

Stacy Thomas, 205/971-8488

or [e-mail]

or

Wayne Cranford, 205/971-8737

or [e-mail]