System, server and method for calculating data volume of network access

A system for calculating data volume of network access is provided, which includes at least one eNB and a core network. The eNB is coupled to two mobile devices. The core network includes two servers. The first mobile device operates as a mobile access point for the second mobile device to access a computer network through the eNB and the core network. The eNB and the core network provide charging data record (CDR) of one of the two mobile devices for accessing the computer network. The first server provides separation information. The separation information indicates the binding relationship between a network address of the second mobile device and the other one of the two mobile devices. The second server calculates data volume of network access of the two mobile devices separately according to the CDR and the separation information. The second server may further bill the two mobile devices separately.