PURPOSE: To control and save telephone usage rate without taking the circumstances into consideration by making trunk line call regulation automatically and compulsorily.

CONSTITUTION: As the relation between usage rate of trunk line telephone and frequency of main wire call is clear, frequency of main wire call can be calculated easily from the limit of telephone rate. Accordingly, the term of telephone rate regulation for each group of users is inputted to a term setting means, and the limit number of times of trunk line call calculated from the limit of telephone rate regulation is inputted to a trunk line call limit setting means 2. On the other hand, objective telephone sets of call regulation at the time of invoking of regulation are classified beforehand and inputted to a regulating means 5, and the content of regulation, for instance, trunk line call from the objective telephone set of call regulation is restricted to local call, is inputted to a regulating means 6. When integration of frequency of trunk line call exceeds the limit of main wire call under above condition, this is detected by a comparing means 4 and a regulation invoking signal is outputted to a telephone regulating means 5 and a content regulating means 6. Accordingly, regulation set by the content regulating means 6 is applied to the telephone set designated by the telephone regulating means 6.