| 摘要 |
The device comprises an electronic management circuit in a protective housing (1) connectable to a telephone handset (13), which circuit includes a microcontroller (2) which performs the following functions: decoding the keypad of the telephone handset (13) using a decoding circuit; transmitting a code to the telecommunications exchange indicating that units are being debited directly from a phonecard connected to said electronic circuit by a card reader (6) for phonecards and particularly smart cards; controlling the release of the telephone line (12); and displaying the used call time units or the calling time still available on the phone card on an alphanumeric display (7). The device further comprises a power supply providing a DC supply voltage for the card and a suitable voltage for erasing units on the phonecard.
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