Abstract: A transmission equipment comprising a center management device collecting data from units connected to subscriber terminals. The center management device includes two processing units and a control unit for controlling operational states of the first and second processing unit in such a way that when one of the two processing units is working, the other of the two processing units is in a standby state. The two processing units process the same data by using a data backup unit whereby all of the units can be made by hardware which may be easily replaced or added. Alternatively, each unit may have a program downloading unit so that if a new function is added or new unit is added, the program in the unit may be down loaded to the center management device.