999 call operators are being balloted over industrial action.
Workers are demanding they are paid a living wage of €11.50 per hour, and calling for an end to what they say are "oppressive working environment and management practices".
The national emergency call service is operated by BT Ireland and Conduit, and the companies have been told the ballot will be conducted within seven days unless there is a "genuine effort" on their part to resolve the issues.
However, the Communications Workers Union claims bosses have refused to discuss pay with staff.
The union's General Secretary, Steve Fitzpatrick, says 999 workers "are delivering a vital public emergency service and they play an essential role in the first responder services to protect life.
"It is unacceptable that they are paid low wages and are forced to endure a petty and vindictive management regime that flouts common decency and the respect that workers are entitled to in the workplace," he adds.
It takes an average of 0.6 seconds for an emergency call to be answered in Ireland - one of the fastest response times in Europe.
The service operates from sites at Eastpoint (Clontarf), Navan and Ballyshannon.
