A Completely Turnkey Contract for PTT Telecom Netherlands By Coherent.

LEESBURG, Va.--(BUSINESS WIRE)--June 11, 1996--Coherent Communications Systems Corporation, the leading echo cancellation and voice enhancement specialist, has completed a major turnkey contract for PTT Telecom Netherlands. The contract was completed in just four months from start to finish, and involved the supply and installation of 600 groups of Coherent's EC-7000 Series 2 digital echo cancellers, together with all ancillary cabling and equipment.

Part of the installation is in support of the international telecoms services under Unisource Voice Service (UVS), a consortium of PTT Telecom, Telia AB, Swiss Telecom and Telefonica. The EC-7000 cancellers are also being deployed across PTT Telecom's phased introduction of SDH (SONET) across its international network.

Coherent was selected for the contract after a two-part evaluation process that originally began in 1991, and was conducted by PTT Telecom during 1994/95. Seven tenders in total were initially considered, followed by a technical evaluation of the proposed echo cancellers. This was initially based on Unisource partner Telia's objective testing of echo cancellation equipment according to ITU G.165 specifications.

The performance of the Coherent EC-7000 units earned a place on the short list for the secondary selection process. PTT Telecom subsequently conducted a series of subjective trials, focusing on the turnkey elements of the program - key criteria were suppliers' ability to meet the specification for quality, maintenance, support, pricing, and an extremely tight delivery and implementation schedule. Coherent was selected on the basis of providing the best match to the PTT Telecom's requirements on all fronts, and the contract was signed in October 1995, with the project timescale running from late November 1995 until the end of February 1996.

Edwin Van Welie, purchaser, and Kees Noordegraaf, Senior Engineer, Network Services International Telecommunications, commented: "We were determined to apply a single contract approach for the complete project - a focus which reflects very closely what is happening throughout PTT Telecom as a whole. Despite having tied down the specification very tightly at the beginning, there were inevitably some changes to the schedule which the Coherent team responded to very well and took in their stride.

The most significant of these involved including the UVS locations as part of the initial implementation, which did not form part of the original plan. We are very pleased with how the whole project went - both parties established a very good, co-operative working relationship."

About the EC-7000 Digital Echo Canceller

The Coherent EC-7000 Series 2 echo canceller represents a state of the art solution for modern wireline and wireless digital cellular networks. Designed to exceed the ITU-T standards, the EC-7000 Series 2 features Coherent's state of the art ASIC devices, providing a flexible and fully future-proof platform for consistent, reliable performance. It has the capability to support both #5, #6 and #7 signalling, without the need for any hardware or software changes. The echo canceller's design also includes optimization features to ensure superior "subjective" voice quality and failsafe facsimile transmission.

Coherent has applied its patented Non-Linear Processor (NLP) techniques to the EC-7000, to deliver fast and stable convergence (50mS for combined ERL and ERLE of 35dB) - a prerequisite for modern network applications. In addition, the unit features local loopback facilities, extensive alarm reporting and self-test diagnostics, as well as significantly reduced power consumption for improved performance with reduced heat generation. The EC-7000 Series 2 supports Coherent's range of application-specific software, enhancing the unit's adaptability for a wide range of problem solving in different network situations.

Software can be remotely downloaded and upgraded, providing a versatile and cost-effective means of maintaining maximum operational flexibility as the network changes. The echo canceller not only supports configuration and control locally, via a hand-held terminal, but also remotely via a PC or other terminal.

Coherent Communications Systems Corporation is a worldwide leader in state of the art voice enhancement technology, spanning echo cancellation platforms and 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, StrataCom, Deutsche 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.

Also available via Internet Web Page: http://www.coherent.com

CONTACT: Coherent

Diane McClelland, 703/729-6400 Ext. 3300

Georgina Garrett at Garrett Axford [phone]

E-mail: [e-mail]