Telephone switch center with control of individual devices

DETAILED DESCRIPTION The problem defined for the invention is to create in a circuit arrangement of the initially stated kind a surveillance possibility, which does not demand that in the activatable individual devices a storage means for device-specific identifications is made available.
The invention solves the posed problem in that after successful connection of a device to the switching network through connect commands and transmission of the start command as well as transmission back of a start command acknowledgement signal, the connect command is one or more times partially or slightly changed, and each time transmitted again, that after each transmission of the changed connect command, the stop command is transmitted by the switching network to the particular device, which has reacted each time to the changed connect command, that each device reacting in this manner responds to the stop command with a stop command acknowledgement signal transmitted back only if after established connection it has received a start command, and that the switching network recognizes an activation error in that it, after transmission of each changed connect command and the stop command transmitted subsequently in each instance receives a stop command acknowledgement signal.
Activated individual devices, therefore, answer all received commands in each instance with a command-specific acknowledgement signal.
After their activation, they always first receive a start command each time and respond to it correspondingly with a start command acknowledgement signal.
If a stop command is transmitted by the central switching device to a conventionally activated individual device, which after its activation has received a start command, then it responds to the received stop command with a stop command acknowledgement signal.
If, however, an activated individual device received a stop command without previously having received a start command, then it does not transmit a stop command acknowledgement signal.
As indicated, now after completed activation of an individual device to the switching device with connect command and after transmission of the start command has taken place in the usual manner as well as transmision back of the start command acknowledgement signal, the connect command is changed one or several times partially or slightly