Enhancement for data session management

A Network Slice Admission Control Function NSACF, keeps track of the current number of Protocol Data Unit PDU sessions existing per Single-Network Slice Selection Assistance Information S-NSSAI that is subject to Network Slice Admission Control NSAC. When an event triggers the number of PDU sessions of a UE within a network slice to increase, then the NSACF checks if the maximum number of PDU sessions for the particular S-NSSAI has been reached and, if so, applies admission control. However, this monitoring may be prone to error particularly in relation to handover of an endpoint terminal from a first access network function (e.g. AMF), at which the endpoint terminal had established data sessions for a network slice, to a second access network function, at which the established data sessions are suspended or at which the network slice is not supported. In this instance, a network management function transmits a notification towards the NSACF comprising information indicative of a reduction of at least one of an endpoint terminal counter for the network slice, and a data session counter for the network slice. This facilitates an accurate count of the current active PDU sessions.