True number portability and advanced call screening in a SIP-based IP telephony system

Custom local area signaling service features offered in the PSTN have certa in limitations due to the closed nature of PSTN network signaling. The adop tion of telephony over IP (IP telephony) will enable a new paradigm of serv ices and features that are not possible to implement in today's PSTN. This is especially the case for services that make use of personal, trusted info rmation, which can be provided by a user's personal digital assistant. In t his article we demonstrate how personal information can be coupled with an IP telephony service to provide user-customized call handling by the networ k. In particular, we describe a demonstration architecture that includes Et hernet-attached phones running SIP, with an interface to synchronize with P DAs that supply personal information. The proposed architecture is quite fl exible; it can support enhanced versions of the current PSTN and private br anch exchange services, in addition to many new features and services. We d escribe true number portability and advanced call screening as examples of new services in a hybrid PSTN/IP telephony environment.