Optus 4G mobile services restored after outage

An earlier Optus outage impacting customers trying to make or receive calls on the 4G network has been resolved.

The company said earlier it was investigating the issue and warned: "mobile service may be interrupted during this time".

"We'll let you know when everything is back in working order. Try setting your handset to 3G, or enable Wi-Fi Calling.

"Use our device guides if you need help with these steps," a statement on the Optus website reads.

The service has now been restored, an Optus spokesperson told Nine.com.au.

"We apologise for any inconvenience and thank customers for their patience."