DE2741214

To facilitate the supervision of long-distance telephone traffic over an extended area, output signals from call monitors associated with a number of trunk lines are fed to respective detectors working into a common preprocessor in which certain parameters of toll calls carried by each of these trunk lines, such as number and length of engagements, number and length of conversations and number of metering pulses, are registered in real time with the aid of respective counters for subsequent transfer to a final processor. The contents of each counter are read out to a buffer memory, within the preprocessor, upon the termination of the respective call or at any time in response to an external command. The preprocessor may be duplicated in order to minimize the effect of malfunctions, with inhibition of the loading and unloading of the counters of either unit until a confirmation signal is received from the other unit or a certain number of operating cycles have elapsed. The final processor can be programmed to determine significant deviations of various aspects of the traffic pattern from a norm.