Wow it has been years since I've received - or even seen - a phone book!
I made a string quilt, no papers needed. Just sew & flip. But I agree with the others, you can get paper that is 10 x 10 or larger at office or art supply stores. If you are going to sew through the paper and rip afterwards, I would recommend vellum. It gets nice and brittle after pressing with steam, and tears quite easily on the perforations.