Callback services, though introduced in Japan almost five years ago, continue to thrive under a certain veil of mystery.

Many Japanese and foreigners alike are a bit suspicious of the cheap and technologically confusing international telephone services, their legality and how the low prices are achieved. After all, most callback companies offer standard rates of 40 yen a minute or lower for a call to the United States, 24 hours a day. But the standard daytime rates of telecom giants Kokusai Denshin Denwa, International Telecom Japan and International Digital Communications can be as much as five times that, at 200 yen to 210 yen a minute. Displeased with the existence of callback, the three telecommunications companies and have recently increased their attempts to restrict it.

"The callback services use KDD's international telephone network without paying KDD a fee and they make it difficult for our other users to have their international calls connected," said Yosuke Fukuma of the telephone giant's public relations office. ITJ and IDC echoed this complaint, saying that the callback services "free-ride" on their circuits to make the initial connection to a callback switchboard and that this should be stopped.