| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication terminal device that can prevent occurrence of a situation that output of voices under calling is suddenly stopped although the voice calling state is continued for a communication partner when an emergency calling origination based on a CSFB function is performed during voice communication calling through a packet data network based on a mobile communication network, and suppress increase of the load of the communication network.SOLUTION: When there is an operation of requesting emergency calling origination during calling through a packet data network, a communication terminal device controls to forcedly cut off the voice communication during calling through the packet data network, and also start emergency calling origination processing. When an under-service cell in which a communication terminal device 10S exists is a cell which is not adaptable to emergency calling origination through the packet data network, the communication terminal device 10S may control to forcedly cut off the voice communication under calling through the packet data network, switch a communication route through the packet data network to a communication route through a line switching network, and start the processing of the emergency calling origination through the line switching network.SELECTED DRAWING: Figure 4 |
