Abstract: A key telephone system includes a terminal and a primary device. The primary device transmits a command for transition into a power-saving state to the terminal, together with a power-saving duration time datum and/or a power-saving deactivating time datum, when the time reaches a power-saving state transition time. The terminal specifies the power-saving duration time and/or the power-saving deactivating time in the timekeeper means, and halts the communication means for communicating with the primary device at the time of receiving the command for transition into the power-saving state from the primary device, and activates the communication means being halted at a time when the timekeeper means has measured the lapse of the power-saving duration time and/or the power-saving deactivating time.

Abstract: A key telephone system includes a terminal and a primary device. The primary device transmits a command for transition into a power-saving state to the terminal, together with a power-saving duration time datum and/or a power-saving deactivating time datum, when the time reaches a power-saving state transition time. The terminal specifies the power-saving duration time and/or the power-saving deactivating time in the timekeeper means, and halts the communication means for communicating with the primary device at the time of receiving the command for transition into the power-saving state from the primary device, and activates the communication means being halted at a time when the timekeeper means has measured the lapse of the power-saving duration time and/or the power-saving deactivating time.

Abstract: Provided are a data communication system, a data communication terminal, a data communication method and a computer program for allowing activation of Web services without need of a plurality of telephone number contracts. In a data communication system where communications are performed between a first communication terminal and a second communication terminal via a network, the first communication terminal includes a control means for controlling the activation of a predetermined Web service on the basis of session information received from the second communication terminal. The session information, which is information using Session Initiation Protocol (SIP), comprises a request destination, a header and a message body. The message body describes session-related information that uses Session Description Protocol (SDP).