| 摘要 |
PROBLEM TO BE SOLVED: To permit a master set side to call a telephone number by automatically transmitting the telephone number registered in a slave set to a master set when the charging state of the slave set is deteriorated. SOLUTION: A slave set is provided with a battery detector 34 monitoring a charging state. When the voltage of a battery E is detected to be dropped to not more than a constant level, telephone number registration data stored in a flash memory 32 is transmitted to a master set-side. The master set registers the data in the idle area of a flash memory 53. When the charging state of the battery E of the slave set is restored, the state is transmitted to the master set and the master set deletes the telephone number registration data for the slave set, which is registered in the flash memory 53. |
