A wireless end-user device (100, 2402), comprising: a modem (1812, 1813, 1814) enabling the wireless end-user device to communicate with a network system over a wireless access network (220, 2404, 2802), the network system comprising one or more servers (121, 122, 123, 127, 132, 160, 172, 180, 182, 240, 340, 350, 1615, 1650, 1652, 1654, 1656, 1658, 1660, 1662, 2804); a user interface (1697, 2512, 3220, 3534); and a first application (2702, 2814, 3010, 3202), a second application (2816, 2818, 3012, 3204, 3206) configured to conduct, in response to a request from the first application, application-layer communication with at least one of the one or more servers to establish a data flow between the second application and the at least one of the one or more servers and to process data received with the data flow from the one or more servers on behalf of the first application; characterised in that the wireless end-user device further comprises: one or more software functions (520, 2406, 2408, 2410, 2502, 2504, 2506, 2510, 2514, 2704, 2708, 2710, 2714, 2718, 3008, 3018, 3212, 3214, 3216, 3218, 3316, 3318, 3322, 3324, 3506, 3508, 3510, 3512, 3514, 3520, 3522, 3524, 3526, 3602, 3606, 3608, 3610, 3612, 3808) configured to: register an association between the data flow and the first application (2702, 2814, 3010, 3202), determine that the data flow is associated with the first application (2702, 2814, 3010, 3202), and based on the determination that the data flow is associated with the first application (2702, 2814, 3010, 3202), implement a service policy; wherein implementing the service policy comprises: determining an accounting of network usage associated with the data flow, and associating the accounting with the first application. a modem (1812, 1813, 1814) enabling the wireless end-user device to communicate with a network system over a wireless access network (220, 2404, 2802), the network system comprising one or more servers (121, 122, 123, 127, 132, 160, 172, 180, 182, 240, 340, 350, 1615, 1650, 1652, 1654, 1656, 1658, 1660, 1662, 2804); a user interface (1697, 2512, 3220, 3534); and a first application (2702, 2814, 3010, 3202), a second application (2816, 2818, 3012, 3204, 3206) configured to conduct, in response to a request from the first application, application-layer communication with at least one of the one or more servers to establish a data flow between the second application and the at least one of the one or more servers and to process data received with the data flow from the one or more servers on behalf of the first application; characterised in that the wireless end-user device further comprises: one or more software functions (520, 2406, 2408, 2410, 2502, 2504, 2506, 2510, 2514, 2704, 2708, 2710, 2714, 2718, 3008, 3018, 3212, 3214, 3216, 3218, 3316, 3318, 3322, 3324, 3506, 3508, 3510, 3512, 3514, 3520, 3522, 3524, 3526, 3602, 3606, 3608, 3610, 3612, 3808) configured to: register an association between the data flow and the first application (2702, 2814, 3010, 3202), determine that the data flow is associated with the first application (2702, 2814, 3010, 3202), and based on the determination that the data flow is associated with the first application (2702, 2814, 3010, 3202), implement a service policy; wherein implementing the service policy comprises: determining an accounting of network usage associated with the data flow, and associating the accounting with the first application. one or more software functions (520, 2406, 2408, 2410, 2502, 2504, 2506, 2510, 2514, 2704, 2708, 2710, 2714, 2718, 3008, 3018, 3212, 3214, 3216, 3218, 3316, 3318, 3322, 3324, 3506, 3508, 3510, 3512, 3514, 3520, 3522, 3524, 3526, 3602, 3606, 3608, 3610, 3612, 3808) configured to: register an association between the data flow and the first application (2702, 2814, 3010, 3202), determine that the data flow is associated with the first application (2702, 2814, 3010, 3202), and