Telstra has blamed a manager for the widespread network outage that affected millions of customers who were unable to make calls or access data for several hours on Tuesday.
The telco's chief operating officer, Kate McKenzie, said the "embarrassing human error" occurred after a malfunctioning node on the network was taken offline.
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Telstra network crashes nationwide
"Human error" causes widespread network interruptions affecting millions of Telstra customers across the country last week.
Instead of reconnecting the servers to one of network's operational nodes, a Telstra worker routed customers back to the dud connection point.
"We took that node down, unfortunately the individual that was managing that issue did not follow the correct procedure, and he reconnected the customers to the malfunctioning node, rather than transferring them to the nine other redundant nodes that he should have transferred people to," Ms McKenzie told reporters on Tuesday afternoon.
"We apologise right across our customer base. This is an embarrassing human error.
"It's not OK. We do not like causing that level of inconvenience to our customers," Ms McKenzie said.
The 10 nodes situated across the network allow the telco to manage traffic and connection for voice and data.
"Normally we could take down three or four of those nodes and do work on them fix them up and it would have no impact, but on this occasion … the correct procedure was unfortunately not followed and the consequences you can see.
"I can now happily say we restored services to all of our customers," she said.
Telstra announced on Tuesday evening that it would be giving all of its mobile customers a day of free data on Sunday.
"Customers don't need to do anything to receive the free data, it will happen automatically for all of our mobile customers," Telstra said in a statement.
The widespread interruption affected customers across the country, with users cut off from making calls on their smartphones, including prepaid devices, and accessing their data.
From 12.45pm red dots lit up the Service Status board on Telstra's website, indicating massive outages in all major cities.
At the height of the interruption, 4663 reports of Telstra problems were logged by aussieoutages.com.
The largest clusters of service failures were in Sydney, Brisbane and Melbourne. Perth, Adelaide and Hobart were also affected.
The telco has confirmed that affected customers are still able to contact emergency services from their mobile phones.
Interruptions to data didn't stop incredulous customers from venting their anger on social media.
"This is ridiculously poor! Not paying my bill this month," Noah Albanese wrote on one of Telstra's Facebook posts.
"Please hurry up, trying to run a business," posted Lyndell Fraser.
The outrage was punctured by a plethora of jokes and memes at the telco's expense, with many users offering the telco rookie IT advice.
Just before 3pm, Telstra said it had identified the issue "and services are being restored progressively".
By 3.30pm, some customers reported that their services had been restored, though the outage was still expected to be affecting millions of businesses and individuals, including 2G, 3G and 4G services.
By 4pm, all services to its mobile customers had been restored, the telco confirmed.