999 operators at the Emergency Call Answering Service centre in Navan are set to go ahead with tomorrow's strike over pay, conditions and union recognition.
Two other centres in Ballyshannon and Eastpoint in Dublin will be running as normal.
The workers are demanding the living wage of at least €11.50p/h, changes to on-call procedures and recognition of their union the Communications Workers Union.
The union has said that 84% of its members at ECAS backed strike action - but has not specified how many workers it actually represents.
The CWU said it had centred the industrial action in Navan to avoid any impact on the vital emergency calls by the public.
BT Ireland, who outsourced the contract for the service to Conduit Global, have clarified that the centre in Navan will remain operational tomorrow, with only an unknown number of CWU members refusing to answer calls between 8am and 8pm.
They say the CWU has not informed them of how many staff will be going on strike.
The company has also said it has contingency plans to ensure services at Navan are not disrupted.
They say they are activating a fourth centre, also in Co Meath, to give them flexibility.
BT say that as part of their contingency plan, they also have additional trained employees in place to handle emergency calls efficiently.
The strike came to public attention when it emerged that employees had limits on time away from their desks including toilet breaks, though the employers say those rules have since been revoked.
The CWU acknowledged that BT/Conduit had stepped up employee engagement as a result of the threat of industrial action, describing this as a calculated and insincere love-bombing of workers with one-to-one chats and group therapy.
However, CWU General Secretary Steve Fitzpatrick claimed the employers had failed to respond adequately to the claims at the heart of the dispute.
He warned that their mandate allows them to extend industrial action if BT/Conduit continue to ignore the claims before them.
The strike has been condemned by Conduit Global which runs the service on behalf of the Department of Communications Energy and Natural Resources.
In a statement, Conduit Global said it was very disappointed that despite what it called the significant progress the company has made with ongoing employee engagement in recent weeks, the union continues to plan strike action.
It said that the average pay of staff was already above the living wage, and that its controversial policy on toilet breaks has been revoked.
It also said that it has changed its suspension and leave policy, and had listened to staff to create a new on-call schedule.
It said elections of staff representatives took place last week - adding that the union did not seem to be up to date with changes taking place in the company and positive feedback from employees.
Conduit Global also noted that the CWU's membership in the company - saying the union did not seem to be up to date on the changes which had taken place within the company.