The increased technical availability provided by mobile communication necessitates support for users so that they can control their personal reachability (personal reachability management). This talk reports on a PDA and mobile phone based prototype functioning primarily as a reachability manager to avoid annoying calls and overcome the CallerID problem. Its core functionality is to enable parties to negotiate, e.g. the urgency of a telephone call, and by that maintain security that respects the interests of all involved parties (multilateral security).
Trials with real-world-users (who used the PDA together with a mobile phone in Heidelberg healthcare) showed that they liked the concept, but want smaller and more integrated devices.
As the usability of the device was crucial and it also allowed users to do simple security operations, e.g. signing a message, it is now being used as the basis for a personal security manager. Personal security managers are important as most fair security and protection measures require that at least some information is held and processed by the users themselves. Some approaches in this direction are presented.