Telstra says its 4G mobile network is now back online after a nationwide issue prevented thousands of customers from making or receiving calls.
"Telstra has resolved an issue impacting some 4G voice calls on its national mobile network. We are sorry that some customers were unable to make or receive calls as this was occurring," a spokesperson said in a statement.
"The issue was caused by technical changes made ahead of upgrades to mobile traffic control equipment in Telstra's Exhibition Street exchange in Melbourne.
"The issue was progressively resolved by reversing the changes. The issue became known about 1:00pm and was resolved about 3:00pm."
For several hours, customers across Australia had been reporting they could not make or receive calls on the 4G network.
The company said it was, "looking into an issue impacting some 4G and NBN voice calls" but the 3G network was apparently unaffected.
Customers complaining about the outage on social media were told Telstra was working to fix the problem as quickly as possible.
"We apologise for an issue impacting some 4G voice calls. Customers who are impacted can switch to 3G to make calls," the company said in a statement.
"Data and 3G services are not impacted. We are working to resolve the issue as soon as possible."
The issue came hours after Telstra announced the launch of its first smartphone plan with unlimited data, "giving customers the freedom to stream, surf and share without worrying about additional data charges".
"We have invested billions in our network, pioneered world-leading 4G speeds and pushed our 4G coverage out to more than 99 per cent of the population," Telstra executive Vicki Brady said in a statement.
"We are now introducing the unlimited plan Australians tell us they want while maintaining the superior network experience they expect."
