Abstract: A cellular telephone device includes: a synchronization unit that establishes synchronization with a base station of a CDMA system beforehand to obtain synchronization information for establishing synchronization with the base station; a storage unit that stores the synchronization information; and a switching unit that establishes synchronization with a base station in a calling zone of the CDMA system corresponding to a calling zone of an LTE system based on the synchronization information, in a case in which a communication request occurs in the CDMA system in a state where a location registration is performed in the LTE system.

Abstract: The cellular telephone device includes a reporting unit and a synchronization unit. In a case in which a communication request occurs in a 3G system in a state where the location registration is performed in an LTE system, the reporting unit reports the communication request, together with data for identifying the 3G system, to the LTE system. The synchronization unit receives synchronization information of a communication channel in the 3G system identified by the LTE system based on such data reported from the reporting unit, and establishes synchronization with the communication channel.

Abstract: The cellular telephone device includes a reporting unit and a synchronization unit. In a case in which a communication request occurs in a 3G system in a state where the location registration is performed in an LTE system, the reporting unit reports the communication request, together with data for identifying the 3G system, to the LTE system. The synchronization unit receives synchronization information of a communication channel in the 3G system identified by the LTE system based on such data reported from the reporting unit, and establishes synchronization with the communication channel.

Abstract: A cellular telephone device includes: a synchronization unit that establishes synchronization with a base station of a CDMA system beforehand to obtain synchronization information for establishing synchronization with the base station; a storage unit that stores the synchronization information; and a switching unit that establishes synchronization with a base station in a calling zone of the CDMA system corresponding to a calling zone of an LTE system based on the synchronization information, in a case in which a communication request occurs in the CDMA system in a state where a location registration is performed in the LTE system.

Abstract: It is possible to provide a wireless communication terminal, a wireless communication terminal communication control method, and a wireless communication system, capable of effectively capturing a communication system, when a transmission operation is performed even if judgment of out-of-service-area is made. The wireless communication terminal (10) includes a control unit (18), a communication unit (11), and a storage unit (17). The control unit (18) stores in the storage unit (17) information specifying a communication system successfully acquired among a plurality of communication systems as a successful history. If a communication start is requested in the state judged to be an out-of-service-area state in which no communication can be performed, the communication system specified by the successful history is made to be an object to be acquired.

Abstract: It is possible to provide a radio communication terminal, a radio communication terminal communication control method, and a radio communication system, capable of effectively performing acquisition of a communication system and trying connection by a communication method desired by a user when a transmission process is generated even if the state is judged to be out-of-cell. When a communication start request is made in the state of out-of-cell in which communication is disabled, a control unit (18) performs an acquisition process start instruction instructing a communication unit (11) to acquire one of communication systems.