Keitai Denjuu Telefang (Japanese: 携帯電獣テレファング; Romaji: Keitai Denjuu Terefangu), often shortened to just "Telefang", is a series of video games developed by Smilesoft. There are two games in this series, namely Keitai Denjuu Telefang 1 and Keitai Denjuu Telefang 2, or more often shortened as Telefang 1 and Telefang 2. Both games have two versions of the game each, Power and Speed.
Keitai denwa (携帯電話) means mobile phone in Japanese, while juu is the word for an animal, or more appropriately here, a monster. Thus, the Keitai Denjuu (携帯電獣) part of the name is a portmanteau suggesting the telephone-using monsters that the series is centered around. Within the game, the word for the monsters is simply Denjuu (電獣).
Telefang (テレファング), the name of the battles the Denjuu participate in, is a romanized Katakana contraction of "telephone" and "fang" with reference to the [D-Shot] telephone and the monsters that use them.
Since Denjuu contains the characters den (電) and juu (獣), meaning "electric" and "monster" in Japanese respectively, the bootlegged version of Telefang 1 referred to them as "electric monsters", which has little to do with the intended meaning of the name.