| 摘要 |
PROBLEM TO BE SOLVED: To provide an interface device transferring data at optimum transmission speed corresponding to the type of a connected key telephone set by changing transmission speed from the first speed to the second speed and transferring data when data transfer at the second speed is decided. SOLUTION: When a key telephone set 11 is connected to an interface card A13, the interface card A13 and a key telephone set 11 transfer data at a low speed mode. When synchronization is established, the interface card A13 transmits a type identification signal request referring to the type of a terminal to the key telephone set 11. The interface card A13 receiving the type of the terminal analyzes the type of the terminal and transmits a transmission speed switch request corresponding to the terminal to the key telephone set 11. Thus, more optimum transfer speed can be recognized by detecting the type signal of the key telephone set 11 and a high speed data transfer processing can automatically and stably be executed.
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