Telstra is suffering a mobile phone and data outage across its Australian network.
Customers in regional areas, along with Sydney, Melbourne and other capital cities, reported an inability to make calls or access the internet using their Telstra post-paid services from 6:30pm.
This is the second outage of Telstra post-paid mobile services in two months.
Comments on may Facebook pages indicate the outage is truly national, with customers from Longreach to Adelaide confirming they are without full service.
The phone and internet giant blamed human error after an engineer caused a nation-wide outage affecting millions of customers for several hours in February by accidentally switching off a core node.
Earlier this month around 500,000 Telstra pre-paid mobile customers also suffered network problems.
Telstra has long relied on its perceived network superiority to justify premium prices. If the latest outage is of a similar scale then it could damage its reputation and help rivals Singtel-Optus and Vodafone Hutchison Australia gain ground.
A spokesperson for Telstra said, "We are aware of an issue affecting some of our mobile customers who are having difficulty making and receiving calls, and using data. 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."