Thousands of Virgin Media O2 staff face redundancy risk as the telecoms firm looks to save money in the face of billions of pounds of debt and tougher competition.
The broadband provider has not finalised the number of roles to be cut but it is likely be a sizeable chunk of its 16,000 workforce, the BBC understands.
VMO2 has billions of debt on its balance sheet and is tackling competition from both smaller providers as well as giants like BT, which has been given regulatory permission to acquire rival TalkTalk, a move which VMO2 has firmly opposed.
VMO2 declined to comment. The Prospect union, which represents VMO2 staff, said the cuts were "disappointing and very unsettling".
Deputy general secretary Noel McClean said it is "committed to supporting our members through what is a difficult time, as well as also working with employers to explore ways to mitigate the number of redundancies and ensure retraining and redeployment of staff affected".