The deal, which has been negotiated under the Government Telecommunications Agreement (GTA), will give Orange access to more than 240,000 mobile users in the public sector.
Pager specialist Pageone Minicall has also cut a deal with the Government under the terms of the GTA, which builds on an existing partnership which had Vodafone as the sole supplier.
Government officials predict that the three-supplier deal will enable the public sector to obtain even greater value for money in purchasing mobile products and services.
A spokesman for the Office of Government Commerce said, "The deal involving Orange, Vodafone and Pageone Minicall offers both choice and value for money to public sector users."
According to officials, the prices have already been agreed with OGCbuying.solutions, the trading arm of the Office of Government Commerce, which means that departments no longer have to re-tender for new products.
Although exact figures were unavailable at the time Computer Weekly went to press, the Government was said to be delighted at the cost savings for the public sector.
Established in April 2000, the Office of Government Commerce was set up to streamline central government procurement.
Earlier this year it negotiated public sector-wide software deals with Microsoft, Sun Microsystems and IBM/Lotus.