A mobile station user is informed of reaching of at least one threshold level of data usage via a wireless communication network in real time. An account of the mobile station user has a maximum data plan limit defined by a user's plan and a data usage balance reflecting an amount of data usage remaining under the plan. When required data usage corresponding to requested data session does not cross the threshold level, a slice of data for the data session is allocated. When required data usage corresponding to the requested data session crosses the threshold level, reduced slice of data is allocated. Data usage is counted in real time during the data session, and a notification of reaching the at least one threshold level of data is sent to the mobile station in real time, at the time when data usage under the mobile station user's account reaches the at least one threshold level.