The damaged cable brought Telstra's services to a virtual standstill all the way from Gosford to the Queensland border last Thursday and Friday, leaving an estimated one million people without telephone, Internet and data communication.
Telstra has steadfastly maintained that an independent organisation was to blame for the chaos caused by the wrecked cable and would be liable for damages.
The Rail Infrastructure Corporation (RIC), which owns and maintains the NSW rail network, had people working in the area at the time, Transport Minister Carl Scully's office has confirmed.
As RIC is a government agency, it has raised the question of whether damages would be picked up by the taxpayer.
RIC would not be drawn on liability, but confirmed that it had a contractor onsite at the time of the mishap.
"RIC is making its own investigation into the work carried out in the area, as is Telstra," a RIC spokesperson said.
"Obviously it will be a very thorough investigation."
Telstra said it would be at least a couple of weeks before the investigation was complete, at which time "we will write to each customer about the event and what action they can take".