Making SIP make cents

The Session Initiation Protocol (SIP) is used to set up realtime sessions in IP-based networks.1 These sessions might be for audio, video, or IM communications, or they might be used to relay presence information. SIP service providers are mainly focused on providing a service that copies that provided by the PSTN (public switched telephone network) or the PLMN (public land mobile network) to the Internet-based environment. Some advantages of using SIP for this purpose are: 1. SIP-compliant elements, including hardphones, softphones, PSTN gateways, or proxies can be used on the network, 2. SIP service providers can easily peer with each other at very low cost over existing IP network connections, and 3. IM and presence service providers are able to federate with each other. Despite these many benefits, however, SIP systems lack an integration with recently introduced identity management solutions in combination with realtime accounting and payments. This article describes how existing SIP deployments address accounting and payments. It also presents a proposal for P2P (peer-to-peer) realtime accounting and payments using SIP in the spirit of federated identity management.