Data protection and data security become more significant since telecommunication services and innovative applications based on these services handle an increasing amount of sensitive data. Modern services, e.g. call forwarding, tele-conferencing, and voice mail services use or store personal data to implement individual services. Sensitive data include personal identities or calling numbers, location information of the communicating parties, service indicators, number translation tables, reachability information, and time and duration of communication events. Generally usable open security services interfaces are proposed, that promote security services implemented in user terminals or Trusted Third Parties in order to satisfy currently ignored and evolving security requirements in a more flexible and scalable way. This approach will both save the huge investments in today's telecommunication infrastructure and promote open security services that are independent of the underlyin...