1. A collector device for real-time, transparent monitoring of application-level data activity on a mobile data network so that the activity may correlated to specific users or aggregated and then reported, the collector device being in communication with a corresponding mobile data network router so that the collector receives substantially all of the data communications from the router and the collector device comprising: a user identity subsystem for correlating phone numbers associated with user mobile devices with IP addresses, wherein said user identity subsystem modifies the correlation of phone numbers to IP addresses in response to the detection of new IP address assignments for the corresponding phone number; a filter to inspect and analyze data communications from the router to detect application-level data level activity, said inspection and analysis being in accordance with specified criteria; a data transfer subsystem for transferring information about the detected and correlated data activity to a data reporting and analysis system.