A six-hour strike at Eircom today led to the cancellation of some of the company's operator services.
11811 inquiry services and operator assistance on 10 and 114 were cancelled.
The dispute, involving 70 staff, is connected to a row affecting a group of workers at the company's mobile wing, Eircell.
The 1200 workers are demanding compensation as they insist they will lose out on £50m worth of stock when transferred to Vodafone.
The four unions involved in the row, IMPACTt, CWU, CPSU and CSPU have warned the company there may be an extension of strike action if the compensation dispute is not resolved.