Four unions are at loggerheads with Eircom over an unpaid 2% pay increase due to them in May as part of the Toward 2016 social partnership deal.

The Communications Workers Union and Impact have given notice of industrial action to commence on 19 July.

Eircom executives refused to confirm if there are off-the-shelf plans they can implement as they face possibly the first serious industrial unrest at the former state telco in 28 years.

Meetings are expected over the weekend "to discuss plans to reduce the possibility of any possible disruption whatsoever", said a spokeswoman for the company, which employs 7,100.

Experts expect the telecommunications network will function "blind" without a full crew on board, even if 5,500 unionised members decide to down tools on 19 July, but common snags such as building contractors accidently damaging underground cabling or an exchange going offline are likely to be major headaches for both management and major customers if unionised network engineers strike.

Unions and management will meet again tomorrow afternoon at the Labour Relations Commission after talks between the two sides broke down on Wednesday.

Communications minister Eamon Ryan is understood to be observing the dispute at Eircom although he is "somewhat circumscribed" in what he can about a private company, according to a Green Party advisor.

"I note the result of the talks between management at Eircom and representatives of the CWU. I would urge both sides to avail of the state's dispute resolution mechanisms before taking any steps that might impact upon the services available to consumers, " the minister said in a statement.

The Department of Communications noted Eircom has responsibilities under its universal service obligations which are enforced by Comreg.

A Comreg spokesman confirmed the regulator has been in contact with Eircom regarding its obligations, which include emergency services call systems, and welcomed the company's decision to take up the invitation by the Labour Relations Commission to mediate in the dispute.

The Communication Workers Union, the largest union in Eircom, said regardless of the form of industrial action it chooses to take, its members had no intention of leaving desks in vital sections such as emergency services.