The deal, which will need to be approved by the UK's competition regulator, would mark end of months of speculation over the future for TalkTalk, which has been on the brink of administration because of its debts.
TalkTalk has 1.5 million retail customers and one million wholesale customers across the UK.
BT chief executive Alison Kirkby said the deal provided "a safety net for the households and businesses who rely on TalkTalk".
This breaking news story is being updated and more details will be published shortly. Please refresh the page for the fullest version.
You can receive Breaking News on a smartphone or tablet via the BBC News App. You can also follow @BBCBreaking on X, external to get the latest alerts.
