As of February 1988, daytime and nighttime (including Saturday, Sunday and holiday) calling charges for direct-dialed calls over 320km (excluding calls to or from mobile units) are reduced by approximately 10%. In addition, charges for calls to offshore islands are reduced by lowering the charge for direct-dialed calls to the most closely related MA on the same basis as charges for calls to adjacent areas, a reduction of 10 yen for up to 80 seconds of calling time. Charges for Okinawa Prefecture as a whole are revised so that tariff distances are computed on the same basis as the rest of the country, using the southernmost MA on the Kyushu mainland as a reference point. Calls between MA's within Okinawa are reduced by 10 yen for up to 80 seconds of time.