Households and businesses across the country will be connected to high-speed broadband in a multi-million-pound plan described as one of the most ambitious in Europe.
Deputy First Minister Nicola Sturgeon announced the £264 million investment, which aims to ensure 85% of properties have access to fibre broadband by the end of 2015.
The total should rise to 95% by the end of 2017, she said.
Early priority will be given to rural small and medium-sized businesses to encourage economic growth in “hard-to-reach” areas.
It builds on previous commitments across the Highlands and Islands.
“Today’s announcement signals the start of one of the most ambitious infrastructure projects in the whole of Europe,” Ms Sturgeon said.
“It will connect communities across rural and urban areas, providing a platform for future economic development and regeneration.”
The project will be delivered by BT, which is investing £106.7m, and is being led by the Scottish Government with councils and the UK Government’s Department for Culture, Media and Sport.
Ms Sturgeon announced the plan at the BT exchange building in Pitt Street, Glasgow, where the contract was signed.
Bill Murphy, BT managing director of Next Generation Access, said: “Having invested significantly in our own commercial project to build a fibre network covering almost 1.5 million premises in Scotland, we’re incredibly excited to be working in partnership with the Scottish Government and local authorities to extend the technology into those mainly rural and remote parts of Scotland that the market alone could not reach.
“We’ll create a platform to support Scotland’s economic and social prosperity.”
UK Communications Minister Ed Vaizey said: “The complex and remote landscape of much of Scotland makes this one of the largest and most challenging projects in our nationwide roll-out of super-fast broadband.”