One hundred and 70 jobs are to go at UPC.
The telecommunications company is to relocate some of its operations to the Philippines.
The majority of the job losses will be in Limerick and Dublin, with a lesser number in Galway, Cork and Waterford.
The company said: "Where possible, redundancies will be achieved on a voluntary basis and it is hoped that available redeployment opportunities will minimise the impact on staff."
SIPTU who represent many of the staff is to begin talks with the company on a voluntary redundancy scheme.