| 摘要 |
First, a checking finds whether there is any called subscriber within the switching system, when a collective command message is received. If none, a negative answer message is transmitted. If any, a positive message is transmitted to give ring to the subs criber, and then, a collective command guide message is connected to the subscriber, as well as enabling a dial counter. Then a dial tone is connected to the subscriber up to the first digit of a secret code, and then, if the secret code is verified, a communication is connected. If the secret code does not correspond, a busy tone is outputted, and a looping is carried out. When a certain roundof looping is carried out, the call is canceled to terminate the call.
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