"We are progressively restoring mobile services and we anticipate returning to normal soon," a Telstra spokesperson said.
"We believe the incident has impacted a proportion of traffic for voice and data across the country.
"The cause of the incident is yet to be determined but at this early stage we understand we have had a problem with the part of the network that allows phones to register and therefore make calls and use data."
"We apologise to our customers for the inconvenience caused," the spokesperson said.
Telstra has acknowledged a fault with its some of its mobile services.
“We are aware of an issue affecting some of our mobile customers who are having difficulty making and receiving calls, and using data,” a spokesperson said.
“We are looking into the cause of this issue and apologise for the inconvenience this is causing. We are doing everything we can to restore services as soon as possible.”
The problem comes on the heels of a major mobile outage for the telco.
In that case the problem turned out to be an error by one of Telstra’s technicians.
Telstra apologised to its customers by offering a free day of data, with mobile users downloading a record-breaking 1841TB of data on the day.