999 operators at the Emergency Call Answering Service belonging to the Communications Workers' Union are to hold a 12-hour work stoppage within the next few weeks.
The date for the industrial action has not yet been revealed, but informed sources anticipated ot would take place before the election.
Earlier, the CWU confirmed that 84% of its members at ECAS backed industrial action in their dispute over pay and union recognition.
It remains unclear whether the union represents a majority of staff at ECAS.
ECAS has 60 employees based at three centres in Dublin, Navan and Ballyshannon.
The Communications Workers Union says the staff are seeking a living wage of €11.50 an hour, union recognition as well as changes to other terms and conditions of employment.
The contract to operate the ECAS service is held by BT Ireland, which outsourced it to Conduit Global.
Both companies have refused to negotiate with the CWU, but have been holding intensive meetings with staff at the three Irish sites since the ballot was announced.
The CWU has claimed that management only started to engage with staff following negative publicity surrounding its restrictions on toilet breaks revealed last week.
According to that policy, staff must report to management before and after taking a toilet break.
Only one ECAS operator is permitted to take a toilet break at any one time across the country.
Every worker is also prohibited from using the toilet for an hour of each working day.
In addition, no toilet break can exceed seven minutes in duration - to a maximum of 19 minutes per 12 hour shift.
If a worker needs more time, they must seek specific permission from line management - and breaches can give rise to what the union described as "severe disciplinary action".
CWU General Secretary Steve Fitzpatrick said that if Conduit bosses wanted to avoid a strike, they would need to address the legitimate requests members had made.
He said it was outrageous that the reaction of BT/Conduit to the ballot was to tell 999 workers that they do not deserve a living wage, and that they will continue to be denied their basic human right to collective bargaining with the support of their trade union.
The Department of Communications, Energy and Natural Resources has said it has been in contact with BT in connection with the industrial action.
In a statement, the Department said BT assured "it has contingency plans in place to ensure that the emergency call answering service is maintained in the event of any industrial action".
Conduit Global has said it is disappointed with the decision, claiming "senior management has opened direct dialogue" with staff.
The company says it is "making significant progress on all issues raised".
The statement adds: "It seems therefore that the CWU is seeking to disrupt the service in an attempt to get Collective Bargaining recognition, which we find very disappointing.
"Conduit Global remains committed to deliver this vital public service and will continue to work with our staff directly to avoid any unnecessary disruption to the Emergency Call Answering Service".
BT has the contract to operate the Emergency Call Answering Service but outsourced it to Conduit Global.
A spokesperson for BT said it was disappointing that a trade union, which was not recognised by BT or Conduit, had decided to take what it called "this unncessary course of action" in relation to the vital emergency call answering service.
The spokesperson said the company was unaware of the details of the union ballot or the number of union members, as they had only learned of this news from the national media.
She said Conduit Global had been working closely with its employees to understand their issues, and had implemented significant changes as a result of that direct dialogue.
The BT spokesperson stressed that BT has a "robust" contingency plan to operate the Emergency Call Answering Service.
Conduit Global also expressed disappointment at the CWU vote.
It said senior management had opened direct dialogue with staff and was making significant progress on all issues raised.
It said that to date, Conduit Global in consultation with staff had reviewed internal policies, taking staff feedback, and was committed to change.
It said management had proposed an interim change to the on-call policy seeking input and feedback from staff.
It also confirmed that when all aspects of remuneration are considered, staff earn in excess of the living wage sought by the CWU.
It said it will continue to work with staff directly to avoid any unncessary disruption to the Emergency Call Answering Service.