1. A wireless end-user device comprising: one or more wireless modems for enabling the end-user device to communicate over at least a first wireless access network; memory configured to store a first wireless access network policy to be applied when the wireless end-user device communicates or attempts to communicate over the first wireless access network, the first wireless access network policy comprising one or more first policy instructions associated with a first service activity, the first service activity including a data communication associated with one of a subset of available applications capable of running on the wireless end-user device less than all available applications capable of running on the wireless end-user device; and one or more device agents configured to perform the following steps, when the wireless end-user device communicates or attempts to communicate over the first wireless access network: determining that a traffic flow is associated with the first service activity, the traffic flow comprising one or more related data transfers or attempted data transfers, assigning a flow tag to the traffic flow, the flow tag comprising a traffic flow identifier configured to assist in preserving the association of the traffic flow with the first service activity when the traffic flow is processed by one or more device functions that operate on the traffic flow, monitoring an attempted or successful first wireless access network service usage associated with the flow tag, the steps of determining, assigning and monitoring occurring in any order, and after determining that the traffic flow is associated with the first service activity, applying the first wireless access network policy to the attempted or successful first wireless access network service usage.