Patent ID: 6556675
Filing Date: 2003-04-29
Classification: H04M,H04Q

Abstract:
A subscriber line control device connected to a plurality of subscriber line circuits, comprising:a hardware including, a scan memory recording signal data for each of the plurality of subscriber line circuits, a comparator comparing received signal data of a subscriber line circuit with signal data recorded in the scan memory, a counter circuit counting times of disagreement between the compared signal data of the subscriber line circuit, a flag memory storing flags, indicating a change of signal data for each of the plurality of subscriber line circuits, and a memory write controller controlling to write the received signal data for updating the signal data previously stored in the scan memory and a flag, the flag indicating in the flag memory that the signal data have changed in the scan memory, when the times of disagreement between the compared signal data of the subscriber line circuit, counted by the counter circuit, reaches a predetermined number; and a firmware periodically monitoring the flag memory to detect the presence of the flag and reading out the signal data from the scan memory, of a subscriber line circuit corresponding to the detected flag.