Optus has confirmed that it suffered an outage on Tuesday night affecting its 4G mobile data and home broadband services.
The outage impacted customers throughout New South Wales, Victoria, and the Australian Capital Territory for around 55 minutes overnight, being restored at around 10.30pm AEST.
"Optus technicians are investigating the cause of the interruption and we apologise to customers and appreciate their understanding," an Optus spokesperson said.
Optus' most recent outage saw a network issue affect text messages being sent between Telstra and Optus customers, with some messages being delayed and others failing to send altogether back in March.
That outage came just days after rival mobile telecommunications provider Vodafone Australia's voice outage, which saw some customers lose voice services for a period of four hours.
Vodafone had attributed its own outage to a fault during scheduled work.
Vodafone also experienced a voice outage lasting around three hours back in January, which was caused by an error during planned work on the network; and a seven-hour 4G mobile outage affecting data, voice, and text messages in September last year, which was caused by a router issue.
Incumbent provider Telstra similarly suffered an outage across fixed-line and mobile services in February due to a fire at its Chatswood exchange, which caused SMS messages to be delivered to the wrong people, and an enterprise voice and data outage caused by faulty hardware in February.
Optus in May announced that it will be investing AU$1.5 billion in its mobile network throughout Australia, attributing the investment to the government's decision not to declare wholesale domestic mobile roaming.
"This decision will provide Optus with the certainty it needs to invest a further AU$1.5 billion in 2017-18 to deepen network capacity and coverage, and continue delivering high-quality services, choice, and competition, particularly in regional Australia," Optus CEO Allen Lew said at the time.
Lew told ZDNet that Optus' goal in investing further in its network is to become the number one network for voice and data in Australia.
"The AU$1.5 billion primarily will go towards our mobile network, and will go towards building a significant number of new greenfields sites primarily in the regional areas," Lew told ZDNet.
"There will also be within that AU$1.5 billion a densification of our metro networks in the capital cities."