This paper presents two methods for securely realizing caller-authenticated and callee-specified calls over telecommunication networks with terminals that accept IC cards having KPS-based cryptographic functions. In the proposed protocols, users can verify that the partner is the proper owner of a certain ID or a certain pen name. Users' privacy is protected even if they do the caller-authenticated and callee-specified calls and do not pay their telephone charge in advance.

Land mobile communications in Japan have shown remarkable progress in recent years. The total number of all types of radio stations has exceeded 750 million as of March, 1992 and more than 80% of them are used for land mobile communications. The more radio telecommunications becomes popular, the more demand for communicating at any time, at any place and with anyone, intensifies. Various new land mobile systems such as digital cellular telephones have been developed and to be introduced. These new systems are designed to promote effective frequency use in order to meet the exploding demand for it. The digitalization of land mobile communication systems will be the key technology which enable to bring the new possibility in the land mobile communications.

Network planning for a public switched telephone network is essentially the same as the company's business strategy. The social environment providing the market for communications services is undergoing rapid change in Japan as it evolves from an era of one basic mainstay service-namely, plain-old telephone service-to one in which a wide range of advanced new services are, or soon will be, available and there is fierce competition to provide those services. This paper covers some of the thinking behind NTT's strategy to put in place a flexible and effectual network that fully reflects the needs and desires of customers in this fast-changing environment.

In the coming information society, people will have to be engaged in the information environment for their everyday activities. We propose a new design concept of Contextual Metaphors for constructing a human interface. It introduces multiple metaphors and makes it easy for people to directly participate into the environment. The major part of the concept is to provide good contextual support for their everyday activities with a layered design of three cognitively distinct concepts. They are the use of everyday based object metaphors, the task oriented assignment of each of metaphors to system functions and the scenario based sequencings of scenes of those metaphors. A prototyping of the concept showed effectiveness of the concept together with some remarks on the actual design.