Shares of Australia's largest telco operator Telstra (ASX:TLS) tumbled to their lowest in nearly seven years on 22 May, after the firm was hit by a second major mobile network service outage in the space of a month.
A software fault on Monday caused multiple elements across its 4G network to fail, and a further fault interrupted the standby hardware, the company said in a statement on Tuesday.
"...some key network equipment failed causing a disruption to 4G voice and data services nationally. The impact was widespread and with a large number of customers dropping back to 3G, there was significant disruption to 3G voice and data services as demand exceeded the capacity of our 3G network," the company said.
On Monday, it had apologised via Twitter for the outage, later tweeting that mobile voice and data services had returned to normal.
Telstra's shares fell as much as three per cent on Tuesday, hitting a low of $2.715, the weakest since August 2011. Its shares have lost more than a fifth of their value so far this year.
The company, which has 17.6 million retail mobile services customers, did not disclose how many people were affected by the outage.
The New South Wales police had issued a statement on Monday asking those affected by the outage to use another carrier or a landline if they needed to call emergency assistance numbers.
Telstra, which faced another outage on April 30 that affected some 4G voice calls, warned earlier this month that its fiscal 2018 results would meet the lower end of its guidance and that challenges would persist into 2019 given the roll out of the National Broadband Network.
The company, like other telecom rivals, is seeing traditional higher-margin streams of revenue dry up, forcing it to rely more on smaller-margin cloud computing and cybersecurity services to corporate clients.
(Reporting by Susan Mathew in Bengaluru; Editing by Sayantani Ghosh and Jacqueline Wong)