Nortel Government Solutions has prevailed in a protest of its $300 million contract to build a voice-over-IP network for the Social Security Administration.

Nortel won the contract in July 2007, but it was protested by AT&T. Now that the protest has been rejected, work on the Telephone Systems Replacement Project can begin, Nortel officials said.

The project is believed to be the largest VOIP deployment in the world and will support 55,000 field office agents. It will include a centrally managed contact center with unified messaging and interactive voice response capabilities.

SSA wants to upgrade and improve its services because the agency anticipates an influx of new users as baby boomers retire, Nortel said.

The agency said it expects the new VOIP network to help consolidate monthly public network service charges, decrease operating and maintenance costs, and establish a platform for future services.

“SSA has confirmed its initial assessment that our combination of software, services, government contracting expertise and world-class Nortel products offers the best value for this project,” said Chuck Saffell, chief executive officer of Nortel Government Solutions, in a statement. “We’ve committed the necessary resources to meet SSA’s aggressive deployment schedule, and we’re eager to get started.”

Implementation will begin immediately. In the first year, Nortel will replace existing telephone systems in 205 of the agency’s nearly 1,600 field offices. The company will replace 500 systems per year after that. The contract also includes network integration operation, maintenance, user support and training.

Nortel is using its Communication Server 1000 switching, Media Processing Server 500 IVR, the Unified Messaging 2000 core platform and CallPilot, and IP Phone 1100 Series handsets.

Nortel’s teammates include General Dynamics Corp., Black Box Network Services, Shared Technologies Inc., York Telecom, High Wire Networks Inc., NetIQ Corp., NetCom Technologies Inc. and Planning and Learning Technologies Inc.

The SSA win joins other government VOIP deployments for Nortel. The company also is working on projects at the Senate and Defense, Energy, Transportation and Veterans Affairs departments, the company said.