Mpower Communications Signs X4 Communications as Master Agent Partner

ROCHESTER, NY -- AUGUST 16, 2004 -- Mpower Communications Corp. (AMEX:MPE), a leading provider of broadband Internet access and telephone services to business customers, today announced an agreement with X4 Communications, one of the nation's largest master agencies, in which X4 is reselling Mpower's full suite of integrated voice and data products in the Chicago market.

"Mpower provides us with a robust product set to offer our customers at a great price, and has an extensive network footprint throughout Chicago," said Steve Braverman, President of X4 Communications. "What's really impressed us is that Mpower pays attention to Agents like no other telecom company I've seen. From the Agent Sales and Support team, to the marketing group and right to the CEO, you can call anyone at Mpower and they are always available. Mpower is quick and nimble, truly understands business and knows how to get things done."

Mpower President of Sales and Marketing Jim Ferguson added, "X4 is a premier master agent in the Chicago market and we are proud to have them representing our products. X4's management team brings years of telecom experience and a special insight specific to the Chicago market. We will look for their input and expertise as we continue to position Mpower as a world-class agent partner."
About X4 Communications

X4 was formed by three independent master agencies to offer premier level telecommunications services to the agent sales channel. Now unified, X4 Communications offers agents a full suite of products, pre/post sales support and soon, access to our fully automated backroom software. X4's mission is to "set the standard for the next generation master agency and provide the best agent experience through unparalleled support and cutting edge technology." www.x4communications.com

About Mpower Holding Corporation

Mpower Holding Corporation (AMEX:MPE) is a facilities-based broadband communications provider established in 1996. Mpower offers a full range of data, telephony, Internet access and Web hosting services for small and medium-size business customers. Further information about the company can be found at www.mpowercom.com.

Forward-Looking Statements

Under the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, certain statements contained in this press release regarding our and/or management's intentions, hopes, beliefs, expectations or predictions of the future are forward-looking statements. These forward-looking statements are not historical facts and are only estimates or predictions. Actual results may differ materially from those projected as a result of risks and uncertainties including, but not limited to, sales growth, changes in federal or state telecommunications regulations, market acceptance of our product and service offerings, the liquidity of our common stock, our ability to secure adequate financing or equity capital to fund our operations and network expansion, our ability to manage growth and maintain a high level of customer service, the performance of our network and equipment, our ability to enter into strategic alliances or transactions, the cooperation of incumbent local exchange carriers in provisioning lines and interconnecting our equipment, regulatory approval processes, the effect of regulatory decisions on our access charges and operating costs, changes in technology, price competition and other market conditions and risks detailed from time to time in our filings with the Securities and Exchange Commission. We undertake no obligation to update publicly any forward-looking statements, whether as a result of future events, new information, or otherwise.