The country's largest public sector union has intensified its industrial action as part of its ongoing campaign against pay cuts and threats to pensions.
Members of the IMPACT trade union have increased industrial action at workplaces in the health, welfare, education, local government and services division.
Beginning today, union members in the health and welfare division are not taking on any work associated with vacant posts.
They are also not doing any work associated with three major HSE projects involving the realignment of cancer care services and the configuration of hospitals in the northwest and the midwest regions.
IMPACT members are also refusing to process any requests for information for parliamentary questions or applications under the Freedom of Information Act.
From tomorrow morning, workers in alternating Health Service Executive areas will stop answering phones for four-hour periods, from 9am until 1pm.
The action begins tomorrow in the Dublin and northeast HSE region and includes voluntary hospitals. However, Emergency Department telephones and the main switchboards in acute hospitals will continue to be answered.
The action moves to the HSE west region on Wednesday, HSE south on Thursday, and HSE Dublin and mid-Leinster on Friday.
IMPACT has given notice of its plans to the HSE this week, but said it may not necessarily do so next week.
Union members working in education and local government and services are also engaged in a work-to-rule and will not be doing the work attached to any vacant posts.
They are refusing to process any representations from TDs and Senators from Fianna Fáil, the Green Party and former members of the Progressive Democrats.
They are also not cooperating with work experience and FÁS graduate programmes, and are continuing to refuse to answer phones on a rolling basis.
CPSU vote in favour of escalation
The CPSU have voted 83% in favour of strike action on a turnout of 76% of members.
Commenting on the result, Blair Horan, General Secretary said, CPSU members have voted decisively for escalating the current dispute over the pay cuts.
At meetings around the country members were shocked and dismayed that the Government would cut their low pay rates by 5-6% while restoring pay levels of senior Civil Service managers on €150,000.