Bilpin Rural Fire Brigade has been forced to turn down a request for assistance and surrounding residents were unable to contact emergency services after a power outage cut communications to the local area.
In a letter to Macquarie MP Susan Templeman, brigade secretary Catherine Wilson stated high winds cut power to the area about 5pm on September 6 and back-up batteries for the Bilpin mobile phone tower then failed, leaving the area without landline, mobile or internet communication.
"The back-up batteries for the Telstra mobile tower ... failed to function sometime between 1am and 5am on Saturday, September 7, leaving the residents of Bilpin and the adjoining communities of Mt Lagoon, Berambing and Mt Tomah without mobile or landline telephone services and internet connection for approximately 14 hours," the letter stated.
"Even more concerning was the fact that the SOS function was not available. Residents were unable to contact emergency services, nor access the SMS alert system.
"[Bilpin brigade] had to turn down a request from Hawkesbury Fire Control to provide a team for the Tenterfield fires as it was impossible to contact our members."
Telstra Regional General Manager Mike Marom responded saying the battery back-up systems at Bilpin and Kurrajong base stations activated following the September 6 power outage and maintained services through to early the following morning.
Mains power was restored on Saturday evening, but the power issue appeared to have triggered a transmission fault at the Kurrajong base station that was repaired on Monday night, he said.
Ms Templeman has contacted Telstra seeking an explanation as to whether the batteries in the tower performed to their specification, but Mr Marom said the Bilpin battery back-ups - installed in 2016 - were in good condition.
"We work towards having a technician on site with a generator when back up battery reserves are running low, however, on this weekend we had over 80 sites impacted in the area due to power issues which made servicing all the base stations very challenging," he said.
"We apologise to the local communities for any inconvenience during this period. We totally understand the frustrations when local communities are left without communications and we do work hard to get services back on track as fast as possible."
Ms Templeman raised the issue in Federal Parliament on September 10, supporting Bilpin brigade's call for the tower's back-up batteries to be supplemented by a generator.
"It isn't good enough ... The back-up batteries at the Telstra tower in Bilpin need to be immediately augmented with a generator before it contributes to a fatality," she told the Lower House.
"Remember, in 2013 Bilpin had to deal with the impact of fire, isolation and extensive power outages as a result of the State Mine fire.
"Throughout my electorate we need better mobile coverage. Some places don't have any."
Outside Parliament, Ms Templeman said the situation was "completely unacceptable".
"This issue of back up battery failure was first raised with me in 2016 and following representations I made to Telstra, we were advised the backup battery had been replaced," she said. "It's clear that battery backup is insufficient for areas like Bilpin, where there is only one tower that provides a vital service."
Ms Templeman met with residents concerned about the impact of the NBN rollout earlier this year, and particularly the reliability of services in an emergency.
"This latest situation will not have done anything to ease their fears," she said.