LOS ANGELES, CA — May 19, 2005 — Mpower Communications Corp. (AMEX:MPE), a leading provider of data and voice services to retail and wholesale business customers , today announced that it has been selected to provide communications services and network connectivity for Elixir Technologies Corporation, a leading developer of production-grade software solutions for document composition, resource management and print stream conversion.

Based in Ventura, California with offices around the globe, Elixir’s business requires an efficient network with high-speed, high-capacity bandwidth to stream and deliver media content and enable voice communications between its counterparts internationally.

Under the three-year service contract Mpower is providing Elixir with dedicated Internet access over a DS3 connection with dynamic bandwidth allocation burstable up to 45 Mbps. Mpower has also installed PRI Trunks to support Elixir’s high volume of domestic and international calls.

“We had separate suppliers for our phones, Internet and voice conferencing and were spending too much for communications. Mpower created a system that was cost effective, reliable and was able to meet the growing needs of our company,” explained Rob Bragenzer, Director of Information Technology at Elixir. “The installation was better than I could have hoped for and service and support have never left me hanging the way my old suppliers did. I know I hired a company, but it feels like I am working with a friend!”

Jim Ferguson, President of Sales and Marketing for Mpower added, “Mpower’s deep and dense VoIP-based network and vast product capabilities offer an ideal solution for growing customers such as Elixir. We are able to provide the broadband network connectivity necessary to support Elixir’s need to transmit bandwidth intensive applications over the Internet. Combining all of their voice and data services with a single provider, Mpower was able to deliver both the personal approach and cost effective solution Elixir required.”

About Elixir Technologies
Founded in 1985, Elixir Technologies has long been a leading developer of innovative software for document composition, resource management and print stream conversion. Elixir specializes in personalized printing and customized business solutions for print, archival systems and the Internet. For more information about Elixir Technologies, call 805.641.5900 or visit www.elixir.com.

About Mpower Communications
Mpower Communications (AMEX:MPE) is 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, Mpower cautions investors that certain statements contained in this press release that state our and/or management’s intentions, hopes, beliefs, expectations or predictions of the future are forward-looking statements. Management wishes to caution the reader that these forward-looking statements are not historical facts and are only estimates or predictions. Actual results, including projections with respect to Mpower’s future operating performance and the revenues and operating income generated by the business acquired from ICG may differ materially from those projected as a result of risks and uncertainties including, but not limited to, our ability to retain ICG customers and to increase revenues from the acquired ICG business, our ability to effectively integrate the ICG business into our operations, unexpected costs of integrating the ICG business into our operations, future 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.