Vodafone Australia has confirmed that it suffered an outage on Tuesday morning affecting customers' ability to make and receive voice calls, which was caused by an error during planned work on the network.
The intermittent disruption of voice services began at 5.30am AEDT, and was resolved by 8.10am AEDT, a Vodafone spokesperson told ZDNet.
Vodafone apologised to its customers for the inconvenience caused by the outage.
The outage occurred following the appointment of acting chief technology officer and general manager for Access Network Delivery Kevin Millroy as CTO in December, following the departure of Benoit Hanssen in July.
As CTO, Millroy is responsible for continuing to expand and upgrade Vodafone's mobile network, as well as overseeing the carrier's entry into the NBN market and working towards the launch of 5G in 2020.
"Kevin knows our network inside out, and has played a critical role in leading the teams which have built the network our customers love and trust," Vodafone Australia CEO Inaki Berroeta said in December.
Vodafone backs up the reliability of its mobile guarantee with a 30-day money-back network satisfaction guarantee.
However, the telecommunications provider also suffered a seven-hour 4G mobile outage affecting data, voice, and text messages back in September last year, which was caused by a router issue.
The router issue subsequently led to such a high number of customers attempting to use the 2G and 3G networks, with a high level of congestion following.
Following that outage, the Australian Telecommunications Industry Ombudsman (TIO) in October announced that complaints about Vodafone during the July to September quarter jumped higher than those about Telstra.
Vodafone, which had previously enjoyed several years of consistently low complaint numbers, saw its number increase substantially over the year, from the 4.1 complaints per 10,000 services in operation (SIO) reported in October 2015 to 6.2 in October 2016.
Telstra's complaints rose from 5.5 per 10,000 SIO during the same quarter in 2015 to six in 2016, apparently having recovered after its own seven outages during the first half of 2016.
In November, market research company Kantar also revealed that Vodafone had dropped customers while Telstra, Optus, Amaysim, and others grew their total market share.
Vodafone Hutchison Australia (VHA) -- which includes numbers from Vodafone, Three, and Crazy John's -- fell by 0.2 percentage points in total market share, down to holding just 14.9 percent of the Australian mobile market as of September 30, 2016.
In prepaid, VHA accounted for 14.6 percent of the market by the end of September, down from 15.3 percent; and in post-paid, it remained stable, at 16.1 percent. The no-contract market segment was the one area where VHA saw growth, rising from 9.9 percent a year earlier to 11.2 percent.
The Productivity Commission's draft report into the universal service obligation (USO), released in December, showed that although Vodafone claims to have 96 percent of the Australian population covered by its network, or 23 million people, only 7.5 percent of the continent's landmass is covered.
By contrast, Optus claims 98.5 percent population coverage and covers 15.6 percent of the nation, while Telstra said it has 99.3 percent of the population and more than 31 percent of the landmass covered by its mobile network.
Vodafone in July reported having a total network customer base of 5.494 million, up 4.5 percent year on year: 3.307 million post-paid customers; 1.679 million prepaid customers; and 508,000 MVNO customers thanks to TPG customers moving from Optus' network to Vodafone's.
Its MVNO customer base rose after Vodafone purchased Lebara last year in September.