A method includes determining, at a network tracking system, a first usage value for a user account during a time interval by applying a first correction factor to a first data value determined from a first cell count of cell counter data retrieved from a network device of a network. The method also includes determining, at the network tracking system, a second usage value for the user account during the time interval based on session information from a plurality of network devices of the network. The method further includes generating a cumulative usage value based on the first usage value and the second usage value.