Feature Interactions in Internet Telephony End Systems

Abstract

Internet telephony end systems can offer many services. Different services may interfere with each other, a problem which is known as feature interaction. The feature interaction problem has existed in telecommunication systems for many years. The introduction of Internet telephony helps to solve some interaction problems due to the richness of its signaling information. However, many new feature interaction problems are also introduced in Internet telephony systems, especially in end systems, which are usually dumb in PSTN systems, but highly functional in Internet telephony systems. Internet telephony end systems, such as SIP soft-agents, can run on personal computers. The soft-agents can then perform call control and many other functions, such as presence information handling, instant messaging, and network appliance control. These new functionalities make the end system feature interaction problems more complicated. In this paper, we investigate ways features interact in Internet telephony end systems and propose a potential solution for detecting and avoiding feature interactions. Our solutions are based on the Session Initiation Protocol (SIP) and the Language for End System Services (LESS), which is a markup language specifically for end system service creation.