DSET Gateway Solutions to Interconnect Mpower Communications with Seven Trading Partners

Bridgewater, NJ - February 28, 2000 - (NASDAQ: DSET) - DSET Corporation, a leading supplier of business-to-business e-commerce solutions for the telecom industry, announced today that Mpower Communications Corp. (formerly MGC Communications, Inc.) will deploy DSET electronic-bonding gateways to automate pre-order and ordering processes. Reflecting Mpower's plans for growth as a competitive local exchange carrier (CLEC), the DSET solutions will facilitate electronic interconnection with trading partners that include Ameritech, the Bell Atlantic North Region, the Bell Atlantic South Region, GTE, Pacific Bell, SBC, and U S WEST.

"Mpower has very aggressive plans to create a nationwide service footprint, and they wanted to deploy automated pre-order and ordering capabilities for all of their trading partners as quickly as possible," said Phil Cavallo, DSET's senior vice president of sales and marketing. "Mpower also required solutions with the openness to quickly interface with their high-performance operations support environment.

"The open API architecture of our electronic-bonding products will enable Mpower to achieve integrated, flow-through operations efficiency almost immediately. We're also set for rapid-fire delivery of all the trading-partner interfaces that Mpower needs to compete in the markets they're targeting across the country."

About Mpower Communications Corp.

Mpower (NASDAQ: MPWR) is one of the country's foremost providers of facilities-based integrated communication services, including Internet, Voice over DSL (VoDSL), local phone service, custom calling features, and long-distance services to small and medium-size businesses. The company currently operates in Southern California (including Los Angeles, San Diego, and Orange County), Chicago, Atlanta, Southern Florida, and Las Vegas. Mpower (then MGC) was recently ranked 12th in the Bloomberg Tech 100 listing of the fastest growing technology companies in the United States based on sales growth for the 1999 fiscal year. Further information about the company can be found at www.mpowercom.com.

About DSET

DSET Corporation is a leading provider of business-to-business e-commerce solutions for the global telecommunications marketplace. The DSET suite of electronic-bonding gateways is designed to interconnect the operations support systems (OSSs) of service providers that must exchange information and share network capabilities as trading partners to provision and maintain a growing range of services for customers in the competitive telecom market. DSET's local number portability solutions play a key role in enabling business and residential customers to change service providers without changing their local phone numbers. DSET is headquartered in Bridgewater, New Jersey, and the company's Web site can be viewed at www.dset.com.

Statements regarding financial matters contained in this press release, other than historical facts, are forward-looking. Since all statements about DSET's plans, estimates, and expectations are based on current projections that involve risks and uncertainties, and are subject to change at any time, the company's actual results may differ materially from expected results. Investors should consider these risks and uncertainties, which are discussed in documents filed by DSET with the Securities and Exchange Commission. These documents identify important factors that could cause the actual results to differ materially from those contained in the projections or forward-looking statements. DSET expressly disclaims any obligation to update any forward-looking statements.

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DSET Contacts:

Media Relations: Kathy Claxton, Corporate Marketing Communications Manager, 908-526-7500 Ext. 1280

Investor Relations: John P. Murphy, Westfield Investor Relations, 908-233-1558, e-mail: westfieldir@worldnet.att.net

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