Seventy per cent of the directory services business Sensis will now belong to a US private equity fund, Platinum Equity.

Telstra chief executive David Thodey said the telco was still required under its carrier licence to make sure printed directories were distributed.

But on ABC radio Mr Turnbull said the government was looking carefully at that rule along with many other regulations.

"In the internet age producing these massive telephone books is really at odds with the way in which most people nowadays access telephone numbers," Mr Turnbull said.

"I think you have to ask yourself how many people actually open a White Pages Directory nowadays to find telephone numbers?

"No doubt quite a lot of people still do, but the majority I would say do not do so any longer."

Age Discrimination Commissioner Susan Ryan said Platinum Equity should be required to distribute phone books as many elderly people relied on them.

For Dubbo resident Muriel Reynolds, 89, who lives alone without the internet, the phone book remains "very important".

As co-ordinator of the Dubbo Senior Citizens Social Group, Mrs Reynolds uses the printed directory to contact other members.

If no longer printed, "it would make it much harder on me because if I want to contact anybody and don't have their number, I won't be able to do it," she said.

"Not everyone can use the computer."

The president of Dubbo's University for the Third Age, which helps older people stay connected, said the book may need to be even thicker to remain useful.

"Comments from our current members indicate that the font size is too small for them to cope with," Colin Jones said.

Independent senator Nick Xenophon echoed the sentiment "you almost need an electron microscope to read the thing".