More than 100 mobile masts are to be erected in a bid to improve coverage in rural areas of Scotland.
Communications companies O2, Three and Vodafone will build and share the infrastructure.
It forms part of a £1bn UK-wide project to help tackle "notspots" - places where there is no mobile phone service.
Masts are to be put up in council areas including Shetland, Orkney, Western Isles, Angus, Argyll and Bute, Dumfries and Galloway and South Ayrshire.
They are to be built in two national parks - Cairngorms and Loch Lomond and the Trossachs.
Sites for masts are also to be sought in Aberdeenshire, East Ayrshire, Highland, Moray, North Ayrshire, Perth and Kinross, Scottish Borders, South Ayrshire, South Lanarkshire and Stirling.
The exact number and location of masts will be subject to the companies finding suitable sites and securing the necessary planning permissions.
The work forms part of the UK-wide Shared Rural Network programme. In Scotland, the completed project will increase 4G coverage from all operators from 42% to at least 74% of landmass.
The programme is scheduled to be finished in 2024.
Separately, communications company EE installed about 100 new masts in Scotland last year and made them available to other operators in line with its commitments to the Shared Rural Network programme.
The Scottish government's connectivity minister, Paul Wheelhouse, welcomed the announcement - saying digital connectivity played "an important role in the nation's social and economic recovery".
He added: "During the current pandemic, this investment in mobile infrastructure, together with commercial builds and government-funded programmes, will keep people safe, protect livelihoods and offer local communities and businesses a vital lifeline."
Last year, the UK government said Scotland, Wales, and Northern Ireland would see the biggest improvements.
In 2018, communications regulator Ofcom said mobile phone coverage in Scotland lagged behind other parts of the UK.
In a report it said only 38% of the landmass had good 4G coverage from all operators - while 82% of England was covered.