Ditech Corporation Chooses the Marben OSI Protocol Stack from DSET for Dense Wave Division Multiplexer.

BRIDGEWATER, N.J.--(BUSINESS WIRE)--Feb. 17, 1999--Ditech Corporation has selected an OSI protocol stack from DSET Corporation (NASDAQ: DSET) for an advanced optical multiplexer system that allows fiber-optic networks to carry substantially more traffic without costly upgrading.

The full seven-layer OSI stack provided by DSET is the software component that will enable the Ditech Dense Wave Division Multiplexer (DWDM) System to interconnect various types of network equipment that use OSI protocols. OSI, which stands for Open System Interconnection, refers to an international standard that employs seven layers of functionality to connect network equipment.

The OSI stack with Intermediate System to Intermediate System (IS-IS) routing was ported onto the Linux operating system from UNIX(R). This was the first use of such an OSI stack with the Linux system. The adaptability and versatility of the OSI protocol stack from DSET made it possible to accomplish the porting in less than 30 days.

For Ditech, the OSI protocol stack is a key part of the DWDM answer to the challenge of helping telecommunications providers meet the fast-growing demand for bandwidth that has been fueled by the growth of the Internet. "We looked at several alternatives, but the OSI stack from DSET was the most efficient solution for porting the necessary capabilities onto Linux," said Salim Jabr, Ditech's vice president of engineering for optical products.

"This innovative use of the OSI stack is another example of DSET's flexibility and efficiency in providing manufacturers with the tools they need to develop software for complex network equipment," added Victor Mak, DSET's vice president of network solutions. "Our application development tools are enabling many of the new capabilities and services in the telecom market."

California-based Ditech Corporation provides voice-enhancement and optical-network products for the telecommunications and cable television industries. In addition to the DWDM System, the company produces echo cancellers to improve the sound quality of telephone voice traffic, optical amplifiers, and systems to monitor and manage the performance of optical networks.

About DSET:

DSET Corporation, founded in 1989, is a leading provider of software and services to the telecommunications industry. The company's application development tools are used by network equipment manufacturers around the world to build applications that manage network components and facilitate the provisioning of new services, such as voice, data, and Internet access. DSET's local number portability (LNP) and OSS interconnection solutions facilitate the flow of information between carriers and their respective operations support systems. The company's services include custom application development, consulting to engineering teams and OSS process teams, as well as interoperability testing, maintenance, and training.

Except for historical and factual information contained herein, all other information set forth in this news release represents forward-looking statements, including all statements about DSET's plans, beliefs, estimates and expectations. These statements are based on current estimates and projections that involve certain risks and uncertainties and could cause actual results to differ materially from those in the forward-looking statements. Investors are encouraged to consider these risks and uncertainties which are discussed in documents filed by DSET with the Securities and Exchange Commission, including, without limitation, fluctuation of quarterly operating results, dependence on a rapidly evolving telecommunications industry, dependence on the TMN industry standard, and the buying patterns of competitive local exchange carriers. DSET undertakes no obligation to publicly update any forward-looking statements whether as a result of new information, future events or otherwise.

DSET's web site can be viewed at www.dset.com.

DSET is the sole provider of Marben(tm) products in the United States and Asia.

DSET and the DSET Logo are registered trademarks of DSET Corporation.

Marben is a trademark of ATOS, France.

UNIX is a registered trademark of X/Open Company, Ltd.