A man uses his mobile phone in front of a Telstra Logo in central Sydney August 13, 2009.
A man uses his mobile phone in front of a Telstra Logo in central Sydney August 13, 2009. Reuters/Daniel Munoz

Telstra’s free data day on Sunday wasn’t exactly what the customers would call a complete success. It was supposed to be a day of free data given by the telco as compensation for its recent outages, but some customers complained of extremely slow speed. Nevertheless, Telstra has now given an explanation on the outages.

Chief Operations Officer Kate McKenzie has addressed the problems the telco has faced recently. In her speech at the CommsDay Summit in Sydney on Monday, she explained that the service interruption on February 9 was due to a rift in the standard operational procedure being followed.

The technical staff had been investigating a fault with one of the signalling nodes that manage 3G and 4G wireless data and voice calls. Unfortunately, processes were not followed properly, and that meant around 15 percent of the telco’s mobile devices connected through the node needed to re-register when establishing a new voice or data session. The mass re-registration overloaded other mobile signalling nodes, and therefore caused further outages.

On March 17, a similar event happened – customers nationwide were unable to make 2G, 3G and 4G voice calls or connect a mobile data session – but McKenzie insisted that the issues were not related.

“The problem was caused when a significant number of customers – initially international roaming customers, and then domestic customers as well – were unexpectedly disconnected from the network. When they all attempted to reconnect at the same time, which happens automatically, we saw a period of overload in the database used to register devices,” she said.

On March 22, some Telstra customers, particularly in Victoria and Tasmania, experienced another network disruption. McKenzie said the incident affected around 3 percent of customers, though she did not give an explanation for it.

The COO said the team has conducted a thorough review of the network.

“I am leading this review and it involves our own specialist teams as well as external experts from around the world. We have already progressed short- and medium-term actions to improve resilience and robustness in the mobile network.”

To compensate the customers for the service interruptions, Telstra offered free data day on February 14 and again in April. But not all customers were happy with the free service.

April 3 was the telco’s second free data day of the year, with customers downloading a total of 2,686 terabytes of data in a 24-hour (or 25-hour in some states) period. However, there were users who complained that their network connection was so bad that they could not even use their Internet to stream AFL and NRL games, which are unmetered on their mobile plans.

Read: Telstra offers free data day on April 3; CEO Andrew Penn says sorry for outage in a big way

Not all customers suffered cripplingly slow speed, though. Sydney resident John Szaszvari clocked in 994GB of free data on that day. He broke his own record on the first free data in February, when he downloaded 425GB of data.

He told Fairfax that he was able to download 14 seasons of “Mythbusters,” 24 seasons of “The Simpsons,” the entire Wikipedia database, Microsoft software, Xbox games updates and “a lot of random other stuff.” He was also able to upload backups of personal files and sync all his Spotify playlists.