Thursday's latest announcement is part of an ongoing overhaul, under which it had already axed 4,000 jobs a year ago.
BT says it is to cut around 13,000 jobs and move some of its offices in a bid to trim £1.5 billion off its costs base.
BT chief executive Gavin Patterson is under pressure from investors to improve the company's stock performance, which has nearly halved over the last two years.
These job cuts and other measures are aimed at helping the telecom reduce its costs by £1.5bn though it does plan to hire an additional 6,000 employees to improve its customer service and network deployment.
The company said the job losses would mainly affect back office and middle management roles, with two thirds of the cuts set fall on United Kingdom staff.
BT had a total of 106,400 employees according to its most recent 2017 annual report.
BT said it wanted "fewer, bigger, more accountable leadership roles" and to "de-layer" its management structures.
It was also trying to improve productivity across its core United Kingdom operations, including "process simplification and automation to reduce costs".
"Many of the roles that BT is proposing to cut are highly skilled professionals and the loss of that expertise could impact BT's research and innovation capability", warned Prospect national secretary Philippa Childs.
"The scale of these job cuts is higher than had previously been speculated on and will come as a devastating blow to managers and professionals represented by Prospect".
"While I recognise the pain, ultimately it is the right thing to do for the business".
BT is focusing on investing ultrafast broadband and to lead in 5G.
Its headquarters near the London Stock Exchange will be closed, although it will still maintain a smaller presence in London at a yet to be decided location.
Moving forward, it said it planned to concentrate its operations on "around 30 modern strategic sites". The restructuring will cost 800 million pounds to implement.
"BT delivered a solid set of financial results in the fourth quarter, with growth in our consumer divisions offset by declines in our enterprise businesses, due to both challenging market conditions and our decision to exit lower margin business", said Chief Executive Gavin Patterson.
BT said the move helped achieve £180 million in savings for the year.
The company has been dealing with the aftermath of an accounting scandal at its Italian division, which resulted in a £530 million write-down and a major fall in its share price past year.