With the introduction of 3G systems multimedia applications over wireless will become widely available to the general public. One such application will be peer-to-peer conversational multimedia communication in which voice, video, still pictures and other media can be used simultaneously and in an interactive way. However, in an all IP environment it is important to have high quality and efficient security services to protect the traffic against eavesdropping and manipulations. In particular, end-to-end security is considered attractive. This paper investigates the security requirements that emerge from conversational IP multimedia applications in heterogeneous environments, with special emphasis on the requirements stemming from the wireless access. The design and the design goals of both SRTP, a security protocol for protection of media traffic, and multimedia Internet keying (MIKEY), a key management protocol specially developed for those environments, are also described.

Klimatologische Mittelwerte der Tagessummen der Globalstrahlung in cal cm−2 für Stockholm wurden aus Solarigraphenregistrierungen der Perioden 1941 bis 1947 und 1949 bis 1956 berechnet und mit früheren Meßergebnissen von Stockholm (Stocksund) verglichen. Der auffallende Unterschied in der relativen Globalstrahlung zwischen Stationen im Tiefland und an Höhen- oder Polarstationen wird diskutiert.