A method and system for providing prepaid billing for two concurrent communication sessions is accomplished by a first-network-access device, such as a WIN SCP, receiving from a prepaid-user account prepaid services for a first-communication session. During the first-communication session, a second-network-access device, e.g., an AAA server, requests from the prepaid-user account additional prepaid services for a second- communication session that is to occur on a data network. In response to the request, the first-network-access device receives from a prepaid-billing system a status-update request. Responsive to the update request, the first-network-access device sends to the prepaid-billing system the prepaid-service usage for the first communication session. The prepaid billing system updates the prepaid user account by debiting the prepaid services usage from the prepaid-user account. If prepaid services remain after updating the prepaid user account, the second-network-access device receives from the prepaid-billing system prepaid services for the second communication session.