AUTOMATIC RECOVERY SYSTEM FOR CCITT NO.5 SIGNAL SYSTEM LINE

摘要

PURPOSE:To rapidly offer a line in which a normal No.5 signal sequence is complete for connecting a call by issuing a test call periodically to another line closed due to a fault which is connected to an international telephone exchange and making the former line vacant automatically. CONSTITUTION:In the case a line comes faulty in the event of temporary disconnection of a signal system line LN 3, a trank TRK 2 is automatically closed under an instruction from a CPU 4, and the CPU 4 periodically transmits a connection control signal to a speech path switch SW 1 to set a channel between a test call generator (ACG) 5 and the TRK 2. The ACG 5 transmits a test call to the LN 3 through the SW 1 and the TRK 2. If the fault in the LN 3 is already recovered at the time when the ACG 5 transmits a start signal by No.5 signal system, a start complete signal is returned, accordingly, the ACG 5 confirms this, then transmits a recovery signal. On the other hand, upon receiving a recovery complete signal returned from the opposite station, the ACG 5 confirms this, then judges that the fault in the LN 3 is recovered, and instantaneously informs the CPU 4 of this. The CPU 4, receiving this information, instructs the TRK 2 to release its closing.