MCI Joins with Nortel Networks to Accelerate Convergence of Voice and Data Networks on Common IP Core

Equipment Deployed throughout Major Metropolitan U.S. Cities Marks Largest Scale Nationwide Deployment of a Next Generation Packet Voice Network ATLANTA, GA, SUPERCOMM, June 3, 2003 - As part of MCI's (WCOEQ, MCWEQ) convergence networking strategy to deliver advanced IP services for businesses and consumers, the company today announced it is joining with Nortel Networks* (NYSE/TSX: NT) to accelerate migration of its voice network to a common IP core. The company has chosen and deployed Nortel Networks' industry-leading Succession* superclass softswitches and Passport* Packet Voice Gateways to create a next generation packet voice network that will fuel innovation, simplicity and value for its customers. "By 2005, MCI plans to move 100 percent of our traffic to an all IP core," said Fred Briggs, MCI President of Operations and Technology. "Nortel Networks Succession voice over packet solution will converge voice, data and multimedia services, helping us to more flexibly and cost-effectively optimize our network. With this implementation, we will increase network efficiency and realize operational savings while providing additional value to our customers." Already well into the first stage of converging its networks onto a common IP platform, MCI has become the first U.S.-based service provider to provision such a large-scale nationwide transition of its full-featured voice service to its core IP backbone. MCI has already deployed 36 Nortel Networks Passport* Packet Voice Gateways. To complete this stage of its strategic migration, MCI plans to deploy another 15 gateways by the end of June. By end of year, MCI plans to have 25 percent of its voice traffic transitioned to its IP core network. Also, as part of its transition to voice over packet, MCI has evolved existing Nortel Networks DMS circuit switches to Succession Communication Server 2000 superclass softswitches. A superclass softswitch is one that meets all criteria for true service provider circuit-to-packet migration - local, tandem and long distance capability on a single platform; full business and residential telephony service sets; regulatory features like "Lawful Intercept" and "Number Portability;" third party interoperability, and carrier-grade reliability and scalability. "With this deployment, MCI represents the largest in-service network of Nortel Networks VoIP equipment in the world," said Sue Spradley, president Wireline Networks, Nortel Networks. "MCI is a fast-moving company that took a very aggressive approach because they saw the immediate benefits to the network and to the business." "Nortel Networks is in a unique position to effectively enable MCI's circuit-to-packet evolution because of our detailed understanding of network design and our comprehensive portfolio. Few vendors are as well positioned as Nortel Networks to help service providers, like MCI, deploy a network so rapidly while extending their existing network investment," added Spradley. Nortel Networks Succession portfolio is the industry's most proven portfolio of voice over packet products, services and solutions for service providers. It enables the delivery of solutions across all four carrier voice over packet market applications: cable, local, long distance and wireless. About WorldCom, Inc.
WorldCom, Inc. (WCOEQ, MCWEQ), which currently conducts business under the MCI brand name, is a leading global communications provider, delivering innovative, cost-effective, advanced communications connectivity to businesses, governments and consumers. With the industry's most expansive global IP backbone and wholly-owned data networks, WorldCom develops the converged communications products and services that are the foundation for commerce and communications in today's market. For more information, go to http://www.mci.com. About Nortel Networks
Nortel Networks is an industry leader and innovator focused on transforming how the world communicates and exchanges information. The Company is supplying its service provider and enterprise customers with communications technology and infrastructure to enable value-added IP data, voice and multimedia services spanning Wireless Networks, Wireline Networks, Enterprise Networks, and Optical Networks. As a global company, Nortel Networks does business in more than 150 countries. More information about Nortel Networks can be found on the Web at www.nortelnetworks.com. Certain information included in this press release is forward-looking and is subject to important risks and uncertainties. The results or events predicted in these statements may differ materially from actual results or events. Factors which could cause results or events to differ from current expectations include, among other things: the severity and duration of the industry adjustment; the sufficiency of our restructuring activities, including the potential for higher actual costs to be incurred in connection with restructuring actions compared to the estimated costs of such actions; fluctuations in operating results and general industry, economic and market conditions and growth rates; the ability to recruit and retain qualified employees; fluctuations in cash flow, the level of outstanding debt and debt ratings; the ability to meet financial covenants contained in our credit agreements; the ability to make acquisitions and/or integrate the operations and technologies of acquired businesses in an effective manner; the impact of rapid technological and market change; the impact of price and product competition; international growth and global economic conditions, particularly in emerging markets and including interest rate and currency exchange rate fluctuations; the impact of rationalization in the telecommunications industry; the dependence on new product development; the uncertainties of the Internet; the impact of the credit risks of our customers and the impact of customer financing and commitments; stock market volatility; the entrance into an increased number of supply and outsourcing contracts which contain delivery and installation provisions, which, if not met, could result in the payment of substantial penalties or liquidated damages; the ability to obtain timely, adequate and reasonably priced component parts from suppliers and internal manufacturing capacity; the future success of our strategic alliances; and the adverse resolution of litigation. For additional information with respect to certain of these and other factors, see the reports filed by Nortel Networks with the United States Securities and Exchange Commission. Unless otherwise required by applicable securities laws, Nortel Networks disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. *Nortel Networks, the Nortel Networks logo, the Globemark, Passport, DMS and Succession are trademarks of Nortel Networks.