Workers at the National Ambulance Service control centre in Dublin will hold a work-to-rule today.
Siptu says its members are concerned over the non-implementation of WRC agreements, staffing levels and payment rates.
The action will affect non-emergency duties at the centre in Tallaght.
Siptu Organiser John McCamley hopes the dispute will be resolved quickly.
He said: "This is just the beginning of industrial action.
"Obviously we are calling on the HSE to intervene, to meet with our members and give reassurance that the Workplace Relations Commission proposals will be implemented."