SIP Providers' Awareness of Media Connectivity
Voice-over-IP (VoIP) has become an important service in the Internet. In contrast to the Public Switched Telephone Network where the delivery of all messages and streams is the responsibility of the calling parties' providers, VoIP media data is sent directly between the user agents without provider interaction in most cases. Hence, a VoIP provider is not aware of media connectivity, i.e., whether a call was successful or not. This may lead to incorrect behavior when a VoIP provider offers services beyond signaling (for example, SPIT prevention, payment). In this paper, the authors discuss several approaches for the detection of media connectivity and present a solution that conforms with the existing standards.