Bushfires royal commission chair Mark Binskin has questioned whether the telcos have focused on commercial considerations rather than the risk to communities, who rely on their services as their primary source of information.

"You are predominantly the major source of information for the community in a system that is now being designed where the community is fed information to be able to make decisions for themselves on when to go, and that's the way the warning system works," he told the major telcos.

"And I will be honest with you, I'm not sure that as a group you've actually looked at it in that way."

Addressing representatives from Telstra, Optus, Vodafone and the NBN, Mr Binskin said there was evidence that previous efforts to get the communications sector to work closer together in understanding the risks had "basically been useless".

About 1400 telecommunications facilities were impacted at the peak of the bushfire season in December and January, largely due to power outages.

The sites targeted for stand-by power systems like batteries and generators tended to be those servicing a large number of customers or part of the core network.

"That seems to be a commercial risk-based assessment rather than necessarily a risk-based assessment based on the environment that's there," Mr Binskin said on Thursday.

If someone's mobile network goes down they can still make triple zero calls through another carrier but cannot get emergency text alerts.

Vodafone said it has been pushing other mobile carriers to develop a SMS roaming ability to enable emergency alerts to get through wherever there is mobile coverage.

Telstra executive Jules Scarlett said there were active conversations about emergency alerts.

She admitted commercial considerations were a significant issue.

"There has to be in any commercial consideration, a consideration of how actually we would still be getting that advantage of having spent the money to invest in regional areas as we have," Ms Scarlett said.

The telcos said they did make assessments about the risk of communities being isolated, or if they were remote or in a bushfire-prone area, when deciding on locations for battery back-up or diesel generators.

Ms Scarlett noted that if mains power was out in a particular area, it may be that none of the providers could provide the service.

Energy providers said they experienced significant delays and difficulties accessing their infrastructure and doing it safely.

Essential Energy executive Luke Jenner said there was an unprecedented scale of destruction to power assets, noting the company had to replace 3200 destroyed poles.

Australian Associated Press