Optus has restored services for the majority of customers affected by an outage in the NSW Hunter region which potentially impacted triple zero calls.
The disruption, caused by vandalism at a mobile phone tower, affected mobile voice and data services for hours for just under 70,000 customers.
It is understood the damage occurred on Maitland Road at Hexham in Newcastle at 9.30am today.
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"We apologise to our customers for the disruption and thank them for their patience," an Optus spokesperson said at 5.45pm.
"We will continue to provide regular updates as work progresses."
The spokesperson said Optus alerted emergency services and agencies, Telstra's emergency call person and relevant government bodies.
It's understood Optus customers were notified just after 1.30pm today.
Telstra confirmed the damage knocked out five of its mobile sites and some landline services in different parts of NSW.
"Repairs are under way and services are progressively coming back online," a spokesperson said.
"Vandalism and copper theft is a significant international issue that affects all service companies, including Telstra.
"The impact of vandalism like this can be significant for businesses, individuals and critical community services.
"It also requires us to divert work crews to restore services, delaying us from resolving other customer issues.
"We encourage anyone seeing any suspicious activity near our facilities to contact police immediately."
A crime scene has been set up and police have appealed to the public for dashcam footage.
Welfare checks are under way in the NSW Hunter region to investigate if there were any failed attempts to connect with emergency services.
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"We're sorry services are still disrupted by an outage," Optus said in an email.
"Calls to emergency services are impacted by this outage.
"Optus customers will only be able to call emergency services if they are within coverage of another mobile network or are able to call via wi-fi."
The outage comes a day after chairman and chief executive Stephen Rue was questioned at a senate inquiry over a triple zero outage in September.
Three customers who were unable to call the emergency line died.
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