More than 200 emergency calls did not get through to dispatchers on Tuesday due to a technical glitch with Ireland's Emergency Call Answering Service.
BT Ireland is contracted to run the service on behalf of the Department of Environment, Climate and Communications.
It says approximately 227 callers were unable to get through between 1.00am and 2.15am on Tuesday morning.
The company says it "quickly restored the service" and that the outage was not malicious in nature.
It also says it provided a list of affected callers to Gardaí, so that they could call people back directly.
"We apologise unreservedly to any caller who may have been affected by this service issue", BT Ireland adds.
A spokesperson for BT Ireland says it is working with the Department of Communications "to ensure a technical error of this nature does not occur again."
Minister of State Ossian Smyth has been briefed on the outage and says the department has sought "a detailed and comprehensive report" on the incident.
The Emergency Call Answering Service (ECAS) is responsible for answering all 112 and 999 calls and texts.
The system handled over 2.3 million calls in 2021.
