Eircom has said it will cut 900 jobs over the next three years with 400 to go by the end of the year.
In a statement today, the telecoms group said the reductions across all areas of business will be achieved through natural turnover and employees leaving voluntarily.
"The restructuring programme is part of the continued focus by Eircom to run an efficient business that delivers greater productivity," Eircom said.
"It will apply to all three of the company's main divisions, including eircom Retail, eircom Wholesale/Networks and the company's Central Services function. The company is currently finalising the details of the programme."
Eircom currently employs just over 7,000 workers.
Australian investment firm Babcock & Brown took a 65 per cent share in eircom in August 2006 with the remainder held by the company's Employee Share Ownership Trust.
The restructuring plan has also seen eircom attempt to solve much of the complaints it has faced with many customers claiming they have waited for months to get connected to phone lines and broadband.
Yesterday Eircom reported a 16 per cent rise in revenue to €1.96 billion in the 12 months to March and a 3 per cent rise in operating profits to €240 million.
The group made operating profits of €60 million in three months to March, reversing a €2 million deficit in the same period last year.
Labour's communications spokesman Tommy Broughan described the proposed job losses as shocking and disappointing.
Mr Broughan said: "The magnitude of the job losses will be of great concern, especially to many members of the Eircom workforce who will be greatly worried about their future job security.
"It is also disappointing that it looks likely that there will be another increase in Eircom's landline phone charges by the end of the year," he added.