Telstra boss Andy Penn has publicly apologised for the telco's latest massive outage that affected about eight million customers for up to four hours.
Scores of customers took to social media to vent their frustration about problems accessing Telstra's mobile and data networks from about 6pm on Thursday.
Mr Penn told reporters in Melbourne on Friday he was "sincerely sorry to all our customers" and said, as happened following a similar outage in February, customers would be offered another data-free day.
He said Telstra had "an issue in the network that caused a number of services to be disrupted at the same time and it was reconnecting that caused extreme congestion" and thus delayed reconnection.
Most services were back up within two hours and the network was fully operating after four hours.
"It affected about 50 per cent of the calls and we have about 16 million customers on our network," he said.
"It goes without question there will be another data-free day and that will be on Sunday, April 3... One outage is not good, is not acceptable but two is absolutely not acceptable."
He said he was committed to doing all he could to ensure no more similar occurrences.
