BT Ignite is to slash more than 2,000 jobs as part of its attempt to become profitable.
The cuts are part of a wider plan to reduce staff numbers at the group by between 5,000 and 6,000 a year for the next three years.
BT's new chief executive, Ben Verwaayen, recently signalled there would be change at Ignite, explaining that it was an area in need of improvement.
Around half of the 2,200 job cuts will be from administration units in the UK, with most coming through voluntary redundancies and natural wastage.
A BT spokesman said that the company was also planning to recruit more than 1,200 additional staff to work in Ignite's sales and marketing areas.
BT has said that it wants Ignite - which provides telecom services to some of Europe's largest companies - to break even by next year, before interest, tax and depreciation.
Cotton seedling freezes to death as Chang'e-4 shuts down for the Moon's 14-day lunar night
Fortnite easily out-earns PUBG, Assassin's Creed Odyssey and Red Dead Redemption 2 in 2018
Meteor showers as a service will be visible for about 100 kilometres in all directions
Saturn's rings only formed in the past 100 million years, suggests analysis of Cassini space probe data
New findings contradict conventional belief that Saturn's rings were formed along with the planet about 4.5 billion years ago