The present invention aims to provide devices for determining to terminate a charging session and Systems thereof. A session termination decision device receives a decision request for terminating a charging processing of the current always on IP connectivity session from a charging session termination request device; the session termination decision device sends information relevant to a termination rule corresponding to the charging session of the current always on IP connectivity session to the initiating device for the charging session, in response to the decision request; and the initiating device for the charging session requests the OCS to terminate the charging session. Compared with the prior art, the present invention releases a Diameter charging session without totally removing the charging rules from IP-CAN, and keeps the IP-CAN session when there is no active service or data flow during long duration session, i.e. the always on IP connectivity session. It will significantly save System resources and reduce unnecessary charges to end users, and thus benefit both service providers and end users.