Presence Interaction Management in SIP SOHO Architecture

A SOHO (Small Office or Home Office) architecture can be sketched as an architecture that involves an ITSP (Internet Telephony Service Provider) and subscribers. The ITSP offers SIP protocol based telephony and presence services for subscribers. A subscriber has a single billing account but several addresses (also called extensions or numbers). Each of those addresses can be assigned to a device, may it be wired or wireless. The subscriber’s set of addresses can be either owned by a single user or by a group of users. In the latter case, each user has one or several addresses. The devices that are presence capable, periodically publish the user presence status to the ITSP presence server. The latter then dispatches this information to other users who have requested to watch the status of that user. If the watched user has more than one device, then more than one status are published. The problem that is addressed arises when the different presence status published about the same user are contradictory. The paper defines the problem of presence status interactions as similar to the known problem of Feature Interactions. Then, a multi-agent architecture, a set of presence interaction resolution policies and a communication language are designed in order to elaborate a solution.