The small print must be tough on advertisers, who pay for their listings, Mr Boyland said.
The new Wanganui telephone directories will be delivered in November, Yellow communications manager Katherine Cornish said.
They will still be a smaller-sized book, but the print will be larger and on directory-grade paper which is less transparent.
The larger print size will be common across 15 New Zealand regions. Ms Cornish said people in larger centres were more likely to look up phone numbers online.
"Particularly in the regions people still really rely heavily on the books," Ms Cornish said.
The number of listings in directories hasn't changed much, she said, despite the advent of cellphones.
People with landlines have an automatic listing, unless they want their number unlisted. A cellphone listing costs an extra $20.80, and a second listing for another surname also costs extra.