Coherent Quality on South American Networks.

LEESBURG, Va.--(BUSINESS WIRE)--Aug. 28, 1995--Leading echo cancellation and voice enhancement technology specialist, Coherent Communications Systems Corp. of Leesburg, Virginia, has been maintaining a high profile in South America, announcing two major South American contracts recently. In Costa Rica, Coherent has supplied its EC-6000 digital echo cancellers to the Instituto Costarricense de Electricidad (ICE), for use on ICE's international exchange in San Jose. In Mexico, Telcel D.F. (a fully owned subsidiary of Telmex) has chosen to install Coherent's innovative Audio Plus wireless voice enhancement software for application across its national cellular network.

The supply of Coherent's leading edge EC-6000 units to ICE is being handled by local agent Bolwar S.R.L, who is also providing training and installation services. Achieving consistently high quality call performance is a top priority for ICE, in line with the country's large and active international business community. The Costa Rican government has invested extensively in recent months, improving and extending the country's telephony infrastructure to provide business users with fast, quality access to international circuits. The Coherent EC-6000 echo canceller was selected on the basis of its proven performance and upgrade flexibility - particularly in conjunction with Coherent's range of software solutions to fine tune the echo canceller for specific network applications. ICE aims to satisfy its total echo cancellation requirements with the Coherent contract.

Quality is also the prime issue behind Telcel's choice of equipment for the growing Mexican digital cellular service. Coherent's Audio Plus software is being used in conjunction with Ericsson's digital cellular system to provide a top quality service. Telcel is confident that this combination will give them a true competitive advantage in what is becoming an increasingly crowded wireless market, with customers selecting equipment on both price and performance. Audio Plus was chosen after extensive tests against competitive systems, during which it consistently delivered significantly better end-user speech quality.

Operating on Coherent's echo cancellation platform, Audio Plus specifically addresses the unique combination of acoustic and network echo encountered on digital cellular networks. The combined effects of the echo types can severely degrade speech quality, negating the enhanced performance of digital cellular operation. Coherent's Audio Plus software ensures that the convergence performance of the echo canceller is maintained at industry leading levels, generally within times of less than 50ms, without any degradation of audio quality.

Coherent Communications Systems Corporation is a worldwide leader in state of the art voice enhancement technology, spanning digital and acoustic echo cancellation platforms as well as associated network software. The company's products are used globally by major commercial telecommunications companies and network operators, including AT&T Wireless, Cellular One, British Telecom, Nokia, Telia, Mercury, Cable & Wireless, Telmex, Stratcom, Deutsche Bundespost Telekom, and France Telecom among the extensive list. Coherent is a fully accredited ISO 9001 company, dedicated to maintaining the highest quality standards at every level.

CONTACT: Coherent Communications Corp., Leesburg

Diane McClelland, 703/729-6400, ext.311

Georgina Garrett at Garrett Axford 44 1273 441200