Eircom said it would investigate the cause of significant disruption to its customers after finally restoring services on Wednesday night.
The glitch initially arose on the network during the morning and lasted for about 10 hours, affecting 5 per cent of daily calls, it said.
It had resulted in intermittent service for customers who use 1800 and 1500 numbers, as well as for some mobile numbers.
Latest on network issue. Service has been returned to customers south of Dublin to Galway & to 11811. See more here https://t.co/8WM8tmq7l9
— eircom (@eircom) September 2, 2015
Just to advise, we are currently experiencing some issues with ISDN landlines and mobile service see more here https://t.co/JxLYhxFRDr
— eircom (@eircom) September 2, 2015
We are advised by #eircom that using landlines to contact emerg servs may be difficult. Some mobiles also affected. This is a national issue
— Dublin Fire Brigade (@DubFireBrigade) September 2, 2015
Great news! We have created a temp number for customers to call whilst the telephone outage is in progress - 0124 83015. Please RT
— Sky Help Ireland (@SkyHelpIreland) September 2, 2015
In a statement last night which appeared to bring the matter to a close, it said: “Services are now stable for customers impacted by Wednesday’s outage.
“The root cause of the incident, which impacted approximately 5 per cent of our daily call volumes, is currently being investigated. Calls to 999 and 112 were not been impacted, and Eircom apologises for any inconvenience caused to our customers.”
Earlier in the evening, operations had been restored to some areas which had experienced disruption to telephone, internet and support lines.
"Service has been returned to customers south of Dublin to Galway and to 11811 [customer care services]," it tweeted.
It had said that since the issue arose at 10am, progress had been made to restore services for customers affected in Dublin and the southern half of the country.
Problematic points
“We have diverted traffic away from problematic points on our network and our engineers continue to work to fully resolve the issue as soon as possible,” it said.
“Calls to 999 and 112 have not been impacted. We apologise for any inconvenience caused to our customers.”
During the day it had been unable to say how many people were affected, but a statement on its website said the fault, as well as affecting 1800 and 1850 numbers, had hit high quality ISDN lines.
Dublin Fire Brigade
In a Twitter post, Dublin Fire Brigade said it had been advised that using landlines to contact emergency services "may be difficult".
However, a later statement said: “We have not been made aware of any instances where a member of the public has not been able to get thought to the emergency services.”
Gas Networks Ireland had also expressed concern, saying "a nationwide fault Eircom is experiencing with phone lines" could affect reporting of gas leaks.
Evalon, the company which processes online payments for terminals in shops and ATM machines, said it was aware Eircom had a problem but was not in a position to comment further.
Speaking on the RTÉ lunchtime news, Paul Bradley, Eircom's director of corporate affairs, described the fault as intermittent and said it was not known if anyone had experienced difficulty in contacting the Fire Brigade or emergency services.
Online statement
In an online statement to customers earlier in the day, Eircom had said calls from eMobile or Meteor networks to the 1890 260260 number for broadband technical support, or to 1800 numbers, would receive a message saying their call could not be taken. This issue had also affected calls into customer care centres.
Businesses including satellite TV provider Sky have also had to make alternative arrangements.
Childline had moved to address some concern over the potential impact on its services. In a tweet, it advised anyone attempting to make contact to do so through its website.
Ahead of a full restoration, the Health Service Executive had said access to all of its services, including the medical card line, had been returned.
Its ambulances had back-up lines in case of emergencies and Tetra radio which it could use to communicate directly with hospitals, and so no issues had arisen, it said.
It was also reported that Comreg, the telecoms regulator, will seek a full report into the incident, the cause of which is likely to be communicated by the company.