Besides the video games, Kodansha also commissioned a manga series to be made for Telefang. They were were serialized in Comic Bom Bom between 2001 and 2002.
The Telefang 1 manga, by Kozue Kino, was serialized in Comic Bom Bom from March 2000 to July 2001. It was later released in 3 volumes, which are still available secondhand from online stores such as Yahoo! Japan Auctions and Amazon Japan. It was never released in English.
The baseball-loving kid Shigeki finds a phone up in a tree, which briefly transports him into the world of the Denjuu. The Denjuu world is a world that is supposed to be off-limits to grade-schoolers. Bewildered, Shigeki tells his classmates about what happened but only his friend Matsukiyo believes him. They decide to test out whether the phone would really take them to the Denjuu world. After they're both transported there they meet with Crypto, the Elder and many other Denjuu, and their adventure begins.
For a detailed list, see the list of Denjuu that appear in the Telefang manga.
While the manga was never officially published in English, a fan-made translation project is in the works. The translated chapters can be found at manga.telefang.net.
The second Telefang manga, by Reigan Raizou (Japanese: 零願雷蔵), was serialized in Comic Bom Bom from February to July in 2002. Unlike the manga based on Telefang 1, it was only published in Comic Bom Bom and never re-released as volumes.