| 摘要 |
PURPOSE:To deal with accidental erasure of information in a volatile storage device due to a worn battery without need of a backup power supply by providing an external storage device storing an identification number and an abbreviation number or the like to the telephone set separately from the portable telephone set main body. CONSTITUTION:An external storage device 15 is provided to the telephone set separately from the portable telephone set main body A. An identification number of the portable telephone set and a manufacture number and an abbreviation number written in a one-time ROM 11 are stored in a memory 16 of the storage device 15. When power of a battery 14 of the main body A is worn, the information written in a RAM 12 is erased. However, after the battery 14 is charged again, when the main body A, an interface 13, and an interface 17 of the storage device 15 are connected and a load instruction is entered by using a key pad 6, the content of the memory 16 of the storage device 15 is written in the RAM 12 of the main body A. |
