Communication plays a central in our society. It affects our private lives as well as business activities. Humans usually observe the environment and the communication partner with all their senses. The perceived information is evaluated to deduce the context of the targeted communication partner. However, distant interpersonal communication does not provide a priori knowledge of the called party's current situation, condition or mood - the callee's context. Current communication systems do not offer satisfying technical means to support context sharing between communication partners. The proposed solution in this paper is based on an enhancement of the Session Initiation Protocol (SIP) for IP Telephony systems. Different mechanism of sharing context among communication peers have been investigated, implemented and evaluated.