Abstract: A method for testing communication paths of an electronic exchange which has at least one pair of time-sharing communication highways and in which a plurality of port circuits are connected to one another in time-sharing fashion through the first and second communication highways. In the method, test data are allotted to prescribed time slots and are transferred to receiving means through the communication highways. The test data are fed back from the port circuits whose hybrid transformers are in non-matching state, then allotted to different time slots, and finally transferred to a dual tone multi-frequency signal receiver through the communication highways.