Public telephone that can read user card and record memory card

摘要

The public telephone is put in place by an service provider who pays the location holder in proportion to usage of the telephone. The telephone unit can read a telephone card (CU) carried by the user, and also a write to a memory card (CP) for the service provider. The insertion of the user card initiates recording of details of the telephone call made by the user in the provider card. An identification process is used at the start of the transaction to validate the user card: the provider card sends a random value to the user card, the user card calculates an authentication value from the random value, this is transferred to the provider card, which accepts the authentication value or not.