A connection to a test trunk circuit and associated test circuit at an outlying central office is dialed from a test center, eliciting a short reply tone pulse as a signal to restore local circuits manually from the dialing to the testing connection. This last operation causes the local circuits to supply an answering tone which causes the remote circuits to be readied for testing until disconnected by operation of a disconnect key at the test center. In order to dispose of accidental calls by third parties to the far end test number, a timer applies a busy tone to the far end line if the answer signal does not appear within 6 seconds after the line is seized.This invention relates to the testing of local telephone subscriber lines from remote testing centers and more particularly to a system for such testing which permits subscriber lines to be tested from any of a number of centers equipped for remote testing.In recent years, test center equipment has been provided for regular testing of subscriber telephone lines which, in addition to facilities for testing the lines of a nearby office or offices, to which permanently connected test trunks (dedicated facilities) provide access, also contain facilities for testing remote offices over voice frequency paths selected as needed from the voice frequency circuits available generally for telephone communication between the office to be tested and an office near the test center.The procedure for testing the lines of offices remote from the test center over voice frequencies not dedicated to rest or service use has in the past utilized arrangements in which an order for a test connection is transmitted over connections which will not be utilized for the test and then an automatic dialing facility at the remote office is caused to set up a connection suitable for tests by generating a call to a test trunk circuit at the test center. That type of arrangement has a number of disadvantages. In the first place it requires the placing of two calls through the switching network connecting the two locations, in the second place it requires the use of two circuits connecting the two locations simultaneously for a short period while the test connection is being set up, thirdly it ties the testing of the particular remote location to the particular test center which the automatic dialing arrangement is programmed to call in, and finally, to simplify identification of the automatically dialled calls coming into the test center, each remote location is arranged to call a different number at the test center to set up a test, a precaution which requires a multiplicity of test trunk circuits at the test center.It is a main feature of this invention that testing of the lines of a remote office from a test center is arranged in such a way that only one connection through the non-dedicated facilities of the switching network and of the lines connecting the two locations need be made to set up the testing connection and to utilize it until the tests are completed. This feature not only makes more economical use of the non-dedicated facilities temporarily used for the test, but they enable the elimination of the calling back facilities heretofore associated with the test trunk equipment at the remote location and the reduction of the specialized test trunks at the test center equipped for remote testing to one such circuit per testing operator. The testing operator's time is also saved because the test circuit is more rapidly established by the use of circuits and arrangements of the present invention.