A system and method for generating Call Detail Records (CDR) to optimize network usage notifications to a mobile device subscriber. The system and method can include a billing system module that determines CDR generation parameters for the mobile device subscriber based on the mobile device subscriber's network usage, including increasing CDR generation when the mobile device subscriber's network usage relative to a predetermined quota is high and/or decreasing CDR generation when the mobile device subscriber's network usage relative to the predetermined quota is low. The CDR generation parameters can be applied to control CDR generation for the mobile device subscriber.