Some Triple Zero emergency voice calls in New South Wales, Victoria and Western Australian may be going unanswered after a Telstra cable was cut.
The issue has resulted in "intermittent" receipt of calls to the police, ambulance and fire brigade number.
In NSW, people needing urgent help can call the Police Assistance Line - 131 444 - if they can't get through on 000.
Other states have similar arrangements, but Queensland is not affected by the disruption. Telstra has blamed the problem on a cut cable in NSW.
The cable, running between Orange and Bowral, was severed at 2.05am AEST on Friday "by an unknown party", Telstra said.
Initially, South Australia was also affected, but that situation appears to have been resolved after Telstra workers restored the routers impacted by the cable cut.
But NSW, Victoria and WA are still affected.
"We're working closely with emergency services in those states," Telstra posted on Twitter.
