The Communications, Electrical, Plumbing Union (CEPU), which represents Telstra employees and contractors, has said that since the privatisation of Telstra, the company has let the copper network degrade to a state of "absolute disgrace" that would be unfit to form the basis of the fibre-to-the-node National Broadband Network (NBN).

CEPU official Shane Murphy today fronted the new Senate Select inquiry into the National Broadband Network (NBN), demonstrating anecdotal evidence collected from union members into the state of the copper network, with cables exposed in many places and other cables protected by plastic bags.

Telstra's CEO David Thodey and wholesale head Stuart Lee have recently said that the network is in good condition, and is repaired as required, but Murphy said that since the privatisation of Telstra in the late '90s and the turn of the century, Telstra has "driven a culture of quantity over quality", where employees are "band-aiding the network" quickly and moving onto other jobs.

"Telstra can now not even determine the extent of the damage, or how bad it is. [It has] degenerated to an absolute disgrace and nearly beyond repair," he said.

"Telstra relies upon statistics to continually hide from the real problem of how bad the copper network is. What the union relies upon is actual evidence provided by workers ... at job sites around the country."

Murphy's claim that Telstra is unaware of the status of its network comes just days after Telstra's chief risk officer said that the company is reliant on the public to inform the company when they discover pits suspected of containing deadly asbestos material.

The Department of Communications and the Department of Finance first fronted the committee this morning, where the Department of Communications faced heated questioning from former Communications Minister Stephen Conroy over the Coalition government's proposed fibre-to-the-node network.

Department of Communications Deputy Secretary Ian Robinson confirmed that NBN Co could face a larger fall in revenue than currently projected under the existing plan, due to users unable to take up higher-speed plans on a fibre-to-the-node network, as well as through other factors, such as competing networks like Telstra and Optus' HFC networks.

"The overall revenue impact depends where they are rolling out as an alternative to those areas," he said.

"In an area where only fibre to the node is available, they will not be able to access those [higher-speed plans]."

The department is currently undertaking a review of access to broadband in Australia, as directed by Turnbull in one of the key reviews he promised before the election. But the review will be "high level", Robinson said, with the department to only be looking at the access to ADSL, HFC, and other networks, as well as the availability of fibre transit across the country, rather than determining the quality of the copper network down every street.

The Department of Communications is set to return before the committee tomorrow, along with NBN Co executives who have been summonsed to appear before the committee.

The membership of the committee is made up of three Labor senators and one Greens senator. The Coalition is allowed to appoint three of its own to the committee, but it is understood that the government didn't nominate any senators prior to today's hearing.