BT is aiming to deliver the most demanding broadband roll out the UK has seen in a £146 million programme to provide a fibre network for Scotland's Highlands and Islands.
It says it will make the network available to about 84% of homes and businesses in the region by the end of 2016.
The project is being led by Highlands and Islands Enterprise (HIE), the region's economic development agency, with BT responsible for the installation of the infrastructure.
The programme will involve the provision of 500 miles of new fibre on land, hundreds of miles of fibre access cable to hundreds of street cabinets, and 250 miles of subsea cables over 19 crossings to remote islands. There are also plans for some fibre to premises.
Most of the money is coming from the public sector, notably the Scottish Government's broadband fund and HIE's budget, while BT is contributing £19.4 million.
Bill Murphy, BT Group's Managing Director of Next Generation Broadband, said: "There are incredible obstacles to overcome, not least building a fibre network across some of the most rugged terrain in the UK. And we have huge distances to cover as we lay our cables over the hills and glens and under the sea."
He added that the network will be open to all communications providers on an equal wholesale basis, so that homes and businesses would have a choice of broadband providers.
BT, HIE and local authorities will are to begin work soon on the deployment details.
The programme is the latest step by BT to provide fibre broadband for most of the country. It follows recent announcements of planned roll outs in a number of UK cities and the Scilly Isles.