Sarah Henderson, the opposition's communication's spokeswoman, made two calls to the triple zero network on Wednesday after the service was disrupted by the widespread outage.
Making false calls to triple zero is a criminal offence with a maximum penalty of three years in prison, and Senator Henderson's test calls have been criticised by Labor as irresponsible.
But Angus Taylor said said his shadow cabinet colleague was well within her rights to make those tests calls, criticising messaging from Communications Minister Anika Wells.
"If the minister hadn't been absent for seven hours, Sarah wouldn't have had to do these things," he told reporters in Melbourne on Thursday.
"These actions were not illegal, and they were made necessary by complete and utter failure from this minister, and that should be the focus of the press, and it should be the focus of the nation."
Mr Taylor dismissed suggestions the calls made to triple zero were vexatious or a hoax.
Senator Henderson also doubled down on her decision to make test calls.
"I was simply, as the shadow minister for communications, making those initial calls to work out whether the ... system was actually operating," she told Sydney radio station 2GB.
"I accept the criticism, but what I will say is that I am in a unique position holding this government to account."
Industry Minister Tim Ayres said making the calls at a time when the emergency phone network was being impacted was reckless.
"I was absolutely shocked by that revelation. I just say to Australians, don't do what she did," he told ABC Radio.
"It's utterly irresponsible. I just don't know why anybody would do that, but I'd certainly say nobody should follow her example."
As of Wednesday evening, Telstra had completed almost 400 welfare checks on people who had called triple zero but failed to be connected during the outage.
Of those, six people required emergency assistance while 79 were referred to police for physical welfare checks.
The opposition leader also was forced to defend earlier comments questioning whether there was a link between the Telstra outage and a Chinese missile test in the Pacific on Monday.
Mr Taylor denied it was irresponsible to make a connection, when the cause of the outage was later revealed to be an internal software issue.
"When you haven't even had a minister or prime minister out explaining what's going on, of course Australians are asking questions, and that was a reasonable question to ask," he said.
"It's always a reasonable question to ask with a cyber attack."
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