Convenience is improved when a mobile telecommunication terminal uses a fixed telephone line. The mobile telecommunication terminal to perform communication via a mobile telecommunication network by cellular communication is a dual-mode terminal able to be wirelessly communicated (by non-cellular communication) with a communication device such as a fixed telephone or a wireless LAN (Local Area Network) access point. The mobile telecommunication terminal when carrying out signal transmission by accessing the communication device via a fixed telephone line connected to the communication device, obtains a telephone number of the mobile telecommunication using usable cellular communication as notifying information and transmits the information to the communication device. The communication device carries out signal transmission via the fixed telephone line so that the telephone number notified from the mobile telecommunication terminal is transmitted to a signal receiver.