| 摘要 |
This study relates to telephony and data communications. This is a microprocessor-based, free-standing (powered by batteries) electronic box 1 forming an interface between the telephone socket 2 of a private installation on the one hand, and a telephone set 6 and possibly a data communication usage terminal 7 on the other hand. It is protected against attempts at fraud by a key and a seal, and is intended for three basic uses: - exclusion of telephone codes beginning with 16, 19 or 36, except after prior dialling of a confidential code on the telephone set 6; - limitation of a data communication usage terminal 7 to a predefined access code, except after prior dialling of a confidential code on the telephone set 6; - automatic sending of a reduced-tariff data communication access code for a period limited by a clock built into the box. <IMAGE>
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