Optus customers unable to make or receive calls during network outage

Optus users in multiple states have been left unable to make or receive phone calls today after the company's mobile network suffered an outage.

Network users in Sydney, Melbourne, Tasmania, Brisbane and Adelaide were affected by the outage, which saw some people unable to make or receive calls across networks, and others unable to call within the Optus network.

An Optus spokesperson said it is frantically working to resolve the issue.

"We're aware of an issue impacting some customers trying to make or receive calls on our mobile network," a statement posted to Twitter said.

"Our tech teams are urgently working to resolve this. We apologise for any inconvenience.

"Some Optus customers may have experienced intermittent disruptions to voice services this morning as a result of a technical hardware failure. Mobile data services were fully operational and were not affected."

Optus told 9News.com.au that services were restored at around 9.20am.

Enraged customers took to social media this morning to express their concerns about the outage.

The outage comes just a month after the telcom giant faced another service disaster in its World Cup streaming service, Optus Sport, admitting it underestimated customer demand and failed to provide a platform that could cope with serving continuous, watchable vision.

Australian football fans were left furious after paying to watch the tournament only to be hit by technical issues, including playback errors during matches.

The company was forced to offer full refunds as a result of the service debacle and agreed to let SBS show all remaining World Cup group matches.