LOS ANGELES, CA – JULY 28, 2004 -- Mpower Holding Corporation (AMEX:MPE), a leading provider of broadband Internet access and telephone services to business customers, today announced its plans to launch a Voice-over-IP (VoIP) Hosted PBX offering in the fourth quarter of this year. Mpower will utilize the hosted IP platform of VocalData, Inc., an application developer of hosted IP telephony solutions.

Mpower’s VoIP Hosted PBX services will further enhance the company’s robust set of facilities-based voice and data products. Mpower was a pioneer in the IP-telephony field and has been offering IP-based services since 1999. Its flagship MpowerOffice product provides VoIP and Internet access on a single T1 with dynamic bandwidth allocation.

The VoIP Hosted PBX application will extend Mpower’s services into the customer premise, providing access to advanced features and functionality remotely through a web portal interface tied directly to an Mpower application server. This solution will offer larger businesses with multiple and/or virtual offices a cost-effective and more robust alternative to traditional PBX and key systems.

“To support the expansion of our IP-based services, we selected a platform from VocalData, a proven market leader in hosted IP applications with outstanding feature and development capabilities, cost-effective solutions and premier partner support,” stated Mpower Communications New Technology Officer Russ Shipley. “Given our financial position, Mpower is able to make investments in broadening our VoIP capabilities to meet the growing needs of our customers while staying within our current CapEx guidance.”

About VocalData

About Mpower Holding Corporation

Mpower Holding Corporation (AMEX:MPE) is the parent company of Mpower Communications, a leading facilities-based broadband communications provider offering 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.