MCI Announces Industry's First Major Deployment of Ultra-Long Haul Network Technology

New Infrastructure to Provide Foundation for Enhanced Service Delivery, Network Performance and Reliability

ASHBURN, Va., FEBRUARY 23, 2004 - MCI (WCOEQ, MCWEQ) today announced it
is deploying a new Ultra Long Haul (ULH) Dense Wavelength Division
Multiplexing (DWDM) optical network, the industry's first major
deployment of its kind. The ULH network will enable MCI to incrementally
set new standards for service delivery, performance, and reliability.
This next-generation transport network will become the foundation by
which all MCI services will be delivered. Today, MCI is carrying traffic on its first ULH network route deployment in the western U.S. and
expects to complete its domestic network build-out over a three to five
year period.

"As we continue to execute on our IP convergence vision, MCI's Ultra
Long Haul deployment signifies a strategic, long-term investment in the
future of all IP communications," said Fred Briggs, president of MCI
Operations & Technology. "We were the first to build a commercial global
IP network, and now we will be the first communications company in the
United States to deploy and activate the optical network of the future
on a broad scale."

The ULH network will allow MCI to dramatically simplify its internal
process of provisioning network capacity from months to weeks, resulting
in better network optimization and utilization for the company. As a
high-capacity all-optical network infrastructure, ULH is capable of
supporting OC-768 core capacity with transmission speeds up to 40Gbps -
four times faster than what has been deployed by service providers
today. Through this implementation, MCI will be able to enhance its
management of network inventory and be much more responsive to customer
demand for bandwidth.

This rapid scalability sets the stage for MCI customers to seamlessly
adopt bandwidth-intensive business applications like Web Services,
multimedia content distribution, grid computing, real-time imaging and
storage networking. The network will also create a platform for future
infrastructure-based services such as protocol-independent wavelength
services and other MCI Private Line service enhancements, which MCI
plans to make available later this year.

"MCI has always engineered its network with an eye on the future," said
Briggs, "By combining our current network infrastructure with next-generation ULH DWDM capabilities, MCI is uniquely positioned to
efficiently manage internal costs in an increasingly competitive
marketplace."

The ULH network will allow transmission systems to extend up to 2000 KM
(up to four times longer than traditional technology) without expensive electronic regeneration equipment. This serves to streamline MCI's U.S. network infrastructure by eliminating thousands of signal regenerators,dramatically reducing both the amount of equipment in the network, and the number of physical connections between network elements. This, in
turn, results in a more cost effective, more manageable and more reliable network.

In addition, ULH technology will allow MCI to provision more capacity on
each fiber than is possible today. This will enable the company to cost
effectively reduce the amount of transmission equipment required to
deliver network capacity. In doing so, MCI's network will be greatly
simplified by consolidating transmission bandwidth onto a common,
reliable, all-optical network infrastructure. This optical network is
designed for reliability by utilizing the time-proven protection of
MCI's ring architecture and will provide diverse traffic routing to
ensure optimum network performance.

MCI's ULH network will be supported by a new and innovative network
management system enabling true end-to-end automation for accurate
monitoring, provisioning and network management. Overall, with fewer
elements and systems to monitor and maintain, ULH allows more efficient
operations without compromising network reliability or security. This
means MCI will be able to better meet its customer's needs while
reducing costs.

MCI has selected CIENA Corporation (NASDAQ: CIEN), and Siemens (NYSE:
SI) as its vendors of choice for the ULH domestic deployment.

About WorldCom, Inc.
WorldCom, Inc. (WCOEQ, MCWEQ), which, together with its subsidiaries,
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, based
on the number of company-owned points-of-presence (POPs), 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.