Abstract: A fraud detector for protecting an electronic device, e.g. a payphone, operating with electronic cards (FC) or chip cards which are inserted in a channel (CH) thereof and thereby connected to the payphone via electric contact elements (C) generally located at the end of the channel. The fraud consists in connecting an external chip card simulator (SIM) to the contact elements (C) by means of fraudulent electric wires (W) inserted in the channel (CH). The fraud detector is an electro- magnetic device which has a first coil (T1) for inducing an AC current in the wires (I) connecting the payphone to the contact elements (C), and a second coil (T2) surrounding the channel (CH) and for detecting this generated current when it flows through the fraudulent wires (W). The presence of the wires (W) is thus detected owing to the current flowing therethrough.

Abstract: A time division multiplex communication system comprised of a plurality of modules, each module being equipped with a space division concentrator and a processor. The modules are interconnected by a control bus and by a plurality of speech busses, the number of speech busses being equal to the maximum number of modules. All busses are connected to each equipped module. The control bus is commonly connected to all modules and this bus is, in turn, controlled by a control circuit. In the control circuit, there is a flip-flop for each module for enabling a scanner in the control circuit to set the address of a module seeking use of the control bus. The processor in the module seeking service recognizes its address and transmits its call processing data on the control bus. Each speech bus is comprised of eight wires for parallel PCM bit transmission with time slot interchanging.