Telstra has revealed that a botched update caused the statewide outage in its Next G mobile network today in Queensland.
Engineers from Telstra, Ericsson and support partners of both companies remain on the ground in Queensland trying to fix the problem.
Telstra has attributed the problem to an update made to the telco's core network overnight.
"While they were planned, these changes unexpectedly created issues in the 850MHz mobile phone network serving Queensland," a Telstra spokesman said this afternoon.
"The changes made to the network overnight are being reversed and Telstra technical experts and equipment vendors, including their global support organisations, are working to completely restore services," he said.

"Our technical teams are investigating the detail causes of the outage but our priority right now is to restore all customer services."
The spokesman said the issue had "nothing to do" with a global upgrade to DNS security overnight (DNSSEC) - an upgrade which came online immediately in the hours before Telstra's Next G network failed.
Late last week, iTnews readers ran tests on the state-based DNS server addresses of Telstra Mobile network and found some to be non-compliant with DNSSEC.
However, Telstra had assured iTnews at the time that it did not expect any impact on customers from the DNSSEC upgrade.
"We looked into it and found the test in question - raised by one of your readers - made assumptions about the configuration of the DNS servers, whereas another test in the suite was successful and works according to our checks," a spokesman told iTnews.
Telstra's Queensland customers have been told that older 2G and 3G networks remain unaffected. Users falling back on these networks can still make and receive calls and SMS, but will experience slower data speeds.
"Customers can check the settings on their device to ensure their phone has automatically roamed onto the alternative networks," Telstra said. "Customers who are unsuccessful connecting a call at their first attempt should wait a short while and re-dial.
"We regret any inconvenience our Queensland customers experienced during the day and thank people for their patience while we work to resolve the issues."
Stay tuned for more...