170 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.
SIPTU is to begin talks with the company on a voluntary redundancy scheme.
The union's Organiser, Dennis Hynes, says it's unacceptable that workers have to witness their jobs being sold off to the Philippines.