Phone books will be printed in a bigger font size after complaints from people who have found the new font too small to read.

Nationals Senate leader Barnaby Joyce has used Senate estimates to ask the Communications Department about the issue.

The department's secretary, Peter Harris, says he has been told by the producer of the phone books, Sensis, that it plans to return to the original font size for certain markets.

"They've advised that they intend to go back to the full-size book for the markets, the regional areas, that have had deep concerns about this," he said.

"I think they're acting in a way to respect the fact that the market has said, in some cases, 'we are quite unhappy about this', and we need to provide a better product."