Eircom has informed staff that it will be seeking 2,000 job cuts between now and June 2014.
Following its emergence from examinership, the company's plan had been to reduce employee numbers by 1,000, but it has now doubled that target.
The company said that it is reducing its workforce of 5,700 to 3,700 as part of a programme to accelerate cost-saving measures and deliver greater operational efficiencies.
Other changes include further modernisation of work practices and consolidation of what it said were under-utilised office locations across the country.
Eircom said that union representatives have been informed and it is its intention that detailed discussions on the programme will commence shortly.
The company exited examinership in June after a five-year survival plan proposed by examiner Michael McAteer was approved by the High Court.
The plan included a proposal to reduce the workforce by 1,000.
The Commuinications Workers' Union said any further staff reductions at Eircom would have to be negotiated, and redundancies would only be on a voluntary basis.