1. A wireless end-user device, comprising: a processor; one or more wireless modems to communicate data for network service usage activities between the device and a selected one of at least a home network and a roaming network; and a non-transitory computer-readable storage medium to store a network service usage activity classification list indicating which of a plurality of background data traffic policies to respectively apply to each of a plurality of applications resident on the device, the plurality of background data traffic policies including at least a first policy that allows background data traffic on a home network type and a roaming network type, a second policy that disallows background data traffic on the home network type and the roaming network type, and a third policy that allows background data traffic on the home network type and disallows background data traffic on the roaming network type; the processor configured to for a wireless network to which the device currently connects through one of the wireless modems in order to communicate data for network service usage activities, classify that wireless network to one of the home network type and the roaming network type to form a first classification, classify that a particular application is currently operating according to a background application classification, determine, for the particular application and based at least in part on the network service usage activity classification list, which of the plurality of background data traffic policies applies to the particular application, and selectively allow or deny one or more network service usage activities by or on behalf of the particular application, by applying, based on the first and background application classifications, the determined applicable background data traffic policy to the one or more network service usage activities.