Mpower Communications Closes $250 Million Debt Offering

Plans Metro Fiber Network Purchase

Rochester, NY -- March 27, 2000 -- Mpower Communications Corp. (NASDAQ: MPWR), a facilities-based provider of broadband data, Internet and telephony services to business customers, today announced that it has closed on the sale of $250 million of 13% Senior Notes due April 1, 2010.

Mpower plans to use the proceeds of the offering to fund capital expenditures, including augmenting its national Digital Subscriber Line (DSL) build-out with metropolitan fiber rings to connect the company's collocation facilities within major markets. The funding will also be used for market expansion, working capital, general corporate purposes, and, potentially, acquisitions.

About Mpower Communications

Mpower Communications (a/k/a MGC Communications, Inc.) is a leading provider of facilities-based integrated communication services including Internet, Voice over DSL (VoSDSL), local phone service, custom calling features and long distance services to business customers. The company currently operates in Southern California (including Los Angeles, San Diego and Orange County), Chicago, Atlanta, Southern Florida and Las Vegas. Further information about the company can be found at http://www.mpowercom.com.

Certain statements contained in this press release that state Mpower Communications and/or management's intentions, hopes, beliefs, expectations or predictions of the future are forward-looking statements. Management wishes to caution the reader these forward-looking statements are not historical facts and are only estimates or predictions. Actual results may differ materially as a result of risks and uncertainties including, but not limited to, projections of future sales, returns on invested assets, regulatory approval processes, market conditions and other risks detailed from time to time in Mpower's Securities and Exchange Commission filings.

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