| 摘要 |
PROBLEM TO BE SOLVED: To enable an operator of a terminal to freely change the encryption scheme during VOIP communication or the like using an IP-PBX and to enable the operator of the terminal to select sound quality and security depending on the situation for improving convenience. SOLUTION: The encryption scheme between a communication terminal device 2A and another device 2B which communicates with the communication terminal device 2A is changed while the communication terminal device 2A and the other device 2B establish communication. The operator can select the optimum security based on his or her own judgement on the importance of the information during communication. The communication terminal device can be turned into an IP telephone apparatus and can establish communication with the other device 2B by VOIP communication. The encryption scheme may be changed by dial control or depression of a function button of the IP telephone apparatus. The encryption scheme may include a DES system, an ECB mode of an AES system or a CBC mode of the AES system. COPYRIGHT: (C)2008,JPO&INPIT
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