FURIOUS Telstra mobile phone customers could be compensated with free data after a worker's blunder crippled millions of services nationwide.
An investigation has been ordered into an outage that blacked out calls for many customers yesterday afternoon. 
Users also suffered intermittent data disruptions to smartphone email and internet. Red-faced Telstra officials blamed human error.
The outage affected up to 16.7 million services attached to Telstra's 3G and 4G networks and prevented phone calls from connecting to customers' mobile phones, while other users reported complete loss of phone and data services.
An individual not following correct procedure reconnected customers to a malfunctioning "node", equipment that manages voice and data traffic, instead of transferring them to other nodes.
Chief operations officer Kate McKenzie said this had a "flow-on consequence" leading to "massive congestion".
"This is an embarrassing human error. It's not OK," Ms McKenzie said. Telstra NSW media manager David Taylor said the node failure created overwhelming demand that affected users nationwide in a domino effect. "The network is configured to manage this, however in this instance we had issues transferring customers to other nodes which caused congestion on the network for some customers," Mr Taylor said.
The carrier is exploring the option of free data for consumers to "make up for the inconvenience". Services were plunged into chaos from 12.23pm. Customers were progressively restored from about 2.30pm, with all back by 4pm.
The Emergency Services Telecommunications Authority said there was "no discernible" impact on triple zero calls.
"People were still getting through. Triple zero was working as normal," a spokesman said. Most mobiles switch to roaming on an available alternative providers' network when triple zero is called.
Telstra's Twitter social media team took a lighthearted approach to the nightmare scenario, dealing with complaints from around the country with good humour.
When one person suggested someone at Telstra headquarters tripped on a cable, the Telstra reply, accompanied by a wink emoticon was: "nah, we just flicked the off switch as a bit of fun." SEE A MAP OF THE OUTAGES THAT HIT TELSTRA CUSTOMERSADVERTISER.COM.AU