Abstract: A communications terminal interfaces a large number of potential individual telephone subscriber channels with a wide bandwidth, time multiplexed fiber optic or other type of trunk line. A time slot interchanger within the terminal assigns each of the subscriber channel time slots to one of the time slots in the trunk line signal. Data of the individual time slots of a frame of data of all channels is sequentially stored in a random access memory and then read out in a different sequence. A uniquely addressed location is provided in the memory for data of each individual channel. For cases where all channels are not being utilized, the system omits reading and/or writing data into the corresponding memory data locations not being used, thus saving power.