The deal with VanguardMS features fixed quarterly bills for the next two years and a fixed rate of decrease in charges that will cut the company's network costs from £4.6m spent in the past two years to £2.8m for the life of the contract.
VanguardMS is a virtual network operator which uses its bulk-buying powers to offer lower costs to customers.
Richard Edwards, Hanson's business systems director, said, "The deal is structured to provide us with a fixed-rate service decreasing at an attractive rate.
"Another crucial element is that it will see VanguardMS moving towards the most modern technologies we require - ADSL, VPN, GPRS and 3G."
Hanson brought in communications consultants to review the company's existing deals with providers: BT (for voice), VanguardMS and Global Crossing.
Edwards said, "We looked at whether we were achieving value for money and identified that we were not on the best deal. Neither [VanguardMS or Global Crossing] was giving us the best we could get.
"VanguardMS responded positively and woke up to the fact that they were not providing the service we wanted."
The deal has built-in service level monitoring and a three-month termination clause.