The Public Sector Broadband Aggregation (PSBA) contract covers the first public services network (PSN) to go live in the UK, and was one of a number of contracts awarded when the government first initiated the Broadband Aggregation project framework in 2004.
BT, Cable & Wireless and Colt were among a number of other service providers associated with the framework at the time.
The Welsh government deployed its network with Logicalis in 2008. As previously reported, by 2012 it had grown from 1,000 connections to 5,000 spread across 2,500 sites at 100 major organisations, and plans were in place to grow to over 9,000 connections.
The contract was put out to tender last summer, and is understood to be worth more than £400m. It will see the winning provider take charge of IP services at education services, emergency services, hospitals and local council sites across Wales.
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According to the original tender document from 2013, it also provides provision of services into organisations affiliated with the public sector, which could include dentists, opticians, pharmacies and third-sector organisations.
The provider will be expected to maintain best value over the seven-year life of the contract by sub-letting short-term contracts to other providers, and evaluate and trial new networking technologies as they arise.
A BT spokesperson declined to comment. The Welsh government said that the PSBA procurement was "ongoing" and that a definitive conclusion of the process was expected in the autumn. But Computer Weekly sources have confirmed BT is set to win the deal.