Yellow communications manager Charlene White said people needed to call to request a magnifying sheet individually.
"This is a free service. In addition, for those who are legally blind, they can call Telecom and register (with proof of their condition) for the 018 service for free," she said.
The company had made a range of changes to local directories to make the format more user-friendly, she said.
"One of the changes includes making the books smaller so they are easier to use, handle and store."
Before making the changes, the company ran some focus groups to gauge what people thought, Ms White said."People told us that though they would have liked the font size to remain at its original size, they were happy to trade off the slightly smaller font for a book that was easier to use and store. Which means it's now more likely to be kept by the phone and used more regularly."
The company was also committed to being more sustainable, with the new format being more environmentally friendly, she said.