A method is disclosed for authorizing a prepaid network service in a data network. A network end station issues a request for a prepaid network service. At a network node, such as a router serving as a gateway for selecting services, a determination is made about whether a user associated with the end station is authorized to access the prepaid network service. Network traffic from the end station is forwarded to a service provider only when the user is authorized to use the prepaid network service. Specific embodiments provide message flows among a mobile station, gateway support node, router, and authentication server that support providing prepaid services in a packet-switched network for mobile communication. In certain embodiments, a connection is held open for an end station while a prepaid quota value is refreshed at a portal, thereby reducing overhead and precluding the need to repeat user logon steps. Further, unused quota amounts can be returned to the authentication server for use in association with multiple concurrent connections of the same device.