| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time after it is determined that speech communication can not be switched, until speech communication by a packet switching system is restored when switching the speech communication by the packet switching system is switched to the speech communication by a line switching system. SOLUTION: During the speech communication through the packet switching system after a registration request message is transmitted to a call control server through a transmission/reception part 11 and registration is performed, when detecting a system switching request to switch the speech communication from the packet switching system to the line switching system, the control part 13 of the radio communication terminal executes control so as to perform transmission including the timer time before registration erasure in a registration erasure request message requesting the erasure of user registration, and executes control so as to use the speech communication service of the packet switching system before the timer time before the registration erasure elapses in the case where the speech communication can not be switched from the packet switching system to the line switching system. COPYRIGHT: (C)2009,JPO&INPIT
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