Soapstone Networks Participates in World's Largest Carrier Ethernet Interoperability Demonstration at Carrier Ethernet World Congress

Avici Systems' (NASDAQ:AVCI), Soapstone Networks, today announced
that it is participating in the world's largest interoperability test
event at Carrier Ethernet World Congress (CEWC). Its Provider Network
Controller (PNC) (TM) successfully demonstrated interoperability,
including the dynamic establishment of multiple services across a
multi-vendor Provider Backbone Transport (PBT) network.

The CEWC and Interoperability event is endorsed by Metro Ethernet
Forum (MEF) and is taking place in Geneva Switzerland, September 24-27
at the Hotel Intercontinental. The Interoperability event highlights
Carrier Ethernet strengths and incorporates MEF defined Ethernet
services. Over 50 engineers representing 24 vendors constructed the
Interoperability exhibit made up of over 65 devices. The 2007
Interoperability showcase, initiated by the European Advanced
Networking Test Center (EANTC), was first developed and conducted in
Berlin, Germany over a two-week period during August.

The PNC dynamically created multiple services with resilient
backup paths across a multi-vendor network configuration consisting of
Nortel Networks MERS 8600 and Extreme Networks BlackDiamond 12802R
switches as endpoints. In real-time, the PNC received requests for
Ethernet services and computed optimal paths through the network,
accounting for current topology, then signaled the configuration to
each network element to instantiate each service.

The EANTC testing demonstrated the following capabilities of the
PNC:

-- The ability to discover network equipment and associated
topology.

-- The ability to engineer and provision PBT tunnels across
multiple vendors' equipment automatically.

-- The ability to identify the optimum path for PBT tunnels
between endpoints while meeting Service Level Agreement and
QoS requirements while optimizing for commercial business
rules.

-- When required, the ability to create suitable backup PBT
trunks across disjointed parts of the network infrastructure.

According to Ray Mota Ph.D., Chief Strategist and President of
Consulting at Synergy Research Group, "this test represents a major
milestone in advancing the adoption of PBT in carrier networks. Our
research shows that one of the major obstacles to the deployment of
PBT in carrier networks is the lack of interoperability and the lack
of a control plane. Soapstone Networks PNC is the first external
control plane that can be deployed by service providers to dynamically
provision services across a multi-vendor PBT network. This test is a
clear signal to the industry that PBB-TE is ready for carrier
consideration."

"We are very pleased to participate in this ground-breaking
interoperability event," said Esmeralda Swartz, VP Marketing and
Business Development at Soapstone Networks. "The ability to deploy
multi-vendor networks that leverage best-in-class technology is
critical to the success of PBT technology. We look forward to working
with our Carrier Ethernet partners to accelerate the adoption of PBT
technology."

The Soapstone Networks PNC mediates between multiple resource
requests from the OSS services/control layer via a standard SOA based
interface. The PNC dynamically models the available and occupied
capacity of the network, selecting the best path based on modeling
along with any other QoS based constraints. Services on the network
are dynamically migrated to allow the restoration of backup paths in
the event of a hard failure or to allow network equipment to be taken
on/off line. The PNC continuously monitors for SLA compliance as well
as network faults, allowing intelligent fault remediation as well as
fault reporting between network operation and provisioned services.

To learn more visit Soapstone Networks at the Carrier Ethernet
World Congress, Geneva, Switzerland, September 24-28, 2007, where you
can meet with Soapstone experts to discuss how Carrier Ethernet can
meet the technical and business requirements for today's networks.

About Soapstone Networks

Soapstone Networks is at the forefront of an evolution to Carrier
Ethernet by delivering resource control systems that connect NGN
software-constructed services to the new Carrier Ethernet transport
network. Soapstone creates a common control framework that decouples
services from underlying network technologies. The Soapstone solution
dynamically provisions precise, SLA-quality services, continuously
optimizing utilization of network resources to bring orderly,
predictable business-driven behavior to service provider networks. The
future of Carrier Ethernet - www.soapstonenetworks.com.

This release may contain information about Soapstone Network's
future expectations, plans, and prospects that constitute
forward-looking statements for purposes of the safe harbor provisions
under the Private Securities Litigation Reform Act of 1995. Such
forward-looking statements are subject to risks and uncertainties,
which could cause actual results to differ materially from those
anticipated. When used in this press release, the words "will be" and
other similar expressions are intended to identify such forward
looking statements. Such risks and uncertainties include, but are not
limited to, Avici's ability to manage the transition of its core
router business, the early stage of Soapstone Networks, market
acceptance of Avici products, services and enhancements, customer
purchasing patterns and commitments, development of the market place,
reliance on technology and distribution partners, product development
and enhancement, intensity of competition of other vendors,
technological changes and other risks set forth in Avici's filings
with the Securities and Exchange Commission.