A PDSN (18) includes a usage recording agent (19) for distinguishing between nonbillable and billable activity of a subscriber device 12. The usage recording agent (19) creates a record of a total number of bytes transmitted from the PDSN (18) to the RAN (14), counts bytes that are retransmitted from the PDSN (18) for providing a retransmitted byte total, and forwards the retransmitted byte total and the record to an AAA (28) so that the record can be adjusted in accordance with the retransmitted byte total.