The fibre broadband roll-out will deliver services to more than a million people across Scotland over the next four years in a project backed by public and private funds.
Around 400 premises in Buckie, Moray, can now order fibre services and this will rise to more than 5,300 as BT engineers complete the local upgrade in the weeks ahead.
The Digital Scotland Superfast Broadband project is being delivered in two parts, one covering the Highlands and Islands and the other covering the rest of Scotland, with both projects being delivered on the ground by BT.
Deputy First Minister Nicola Sturgeon said: "Today marks an important milestone for the Digital Scotland Superfast Broadband partnership and for the people of Buckie who are the first in Scotland to benefit from this service. It's fantastic news that local households and businesses will now see the benefits of high quality digital connectivity.
"The scale of the challenge of delivering fibre broadband into rural Scotland outstrips any other part of the UK. This is one of the most ambitious broadband infrastructure projects ever to have been undertaken and will see 95% of premises in Scotland covered by 2017/18.
"This is an important step towards ensuring that Scotland has world-class digital connectivity by 2020. Our investment, and that of our partners in the project, will extend access to superfast broadband across Scotland. This will be a key factor in ensuring Scotland's long-term economic prosperity."
The project, funded by a partnership of the Scottish Government, Highlands and Islands Enterprise (HIE), Broadband Delivery UK (BDUK) and BT, will deliver broadband to areas which it was not viable for BT to cover as part of its commercial roll-out.
HIE is leading on the £146 million project for its region and aims to bring fibre services to 84% of homes and businesses by the end of 2016, while other parts of Moray and areas around Inverness are due to go live by this April.
The project will see BT install more than 500 miles of new fibre on land, and another 250 miles of subsea cables connecting the island communities.
Brendan Dick, director of BT Scotland, said: "Taking fibre broadband to the Highlands and Islands is the most challenging engineering project BT is tackling in the UK. It's a massive operation which includes the complexities of laying 20 subsea fibre cables in a six-month weather window kicking off in May, so it's great to see our extensive planning and logistics paying off with a live cabinet here in Buckie.
"The internet is playing an increasingly important part in all our lives - whether it's small businesses keeping in touch with their customers and suppliers, children doing their homework or playing interactive games online, grandparents staying in touch with their grandchildren, or people working from home. Each of these things is made easier, quicker and better by faster fibre broadband."
The £264 million rest of Scotland project is being led by the Scottish Government working together with local authorities and BDUK.
It includes public funding and investment from BT.