The present invention is directed to a compression device including an identifier determination circuit configured to determine a first identifier value identifying a first communication terminal of a network, and a second identifier value identifying a second communication terminal of the network; a differential determination circuit configured to determine a differential value based on a difference between the first identifier value and the second identifier value; and a compressed string generation circuit configured to insert the differential value into a compressed string. A compression method, a decompression device and a decompression method are also disclosed.