A communication apparatus comprising: a transmission unit for transmitting a call request including information on a condition of a wireless communication system of a called side desired by a calling side by use of a predetermined communication system; characterized by the following features: a memory unit for storing a screen state of a display unit at transmission of the call request and an initiation state of an application corresponding to the screen state; a request unit for requesting the called side, when receiving information that the called side uses a wireless communication system not satisfying the condition of the wireless communication system of the called side desired by the calling side in response to the call request transmitted by the transmission unit, to transmit a call enable notification, when the called side can connect to a wireless communication system satisfying the condition of the wireless communication system of the called side desired by the calling side, to notify the calling side accordingly; and a control unit for controlling the display unit, when receiving the call enable notification from the called side in response to the request by the request unit, to display the screen state stored in the memory unit and, when detecting a call instruction in the screen state, an application corresponding to the call instruction to send a call. a transmission unit for transmitting a call request including information on a condition of a wireless communication system of a called side desired by a calling side by use of a predetermined communication system; characterized by the following features: a memory unit for storing a screen state of a display unit at transmission of the call request and an initiation state of an application corresponding to the screen state; a request unit for requesting the called side, when receiving information that the called side uses a wireless communication system not satisfying the condition of the wireless communication system of the called side desired by the calling side in response to the call request transmitted by the transmission unit, to transmit a call enable notification, when the called side can connect to a wireless communication system satisfying the condition of the wireless communication system of the called side desired by the calling side, to notify the calling side accordingly; and a control unit for controlling the display unit, when receiving the call enable notification from the called side in response to the request by the request unit, to display the screen state stored in the memory unit and, when detecting a call instruction in the screen state, an application corresponding to the call instruction to send a call. a memory unit for storing a screen state of a display unit at transmission of the call request and an initiation state of an application corresponding to the screen state; a request unit for requesting the called side, when receiving information that the called side uses a wireless communication system not satisfying the condition of the wireless communication system of the called side desired by the calling side in response to the call request transmitted by the transmission unit, to transmit a call enable notification, when the called side can connect to a wireless communication system satisfying the condition of the wireless communication system of the called side desired by the calling side, to notify the calling side accordingly; and a control unit for controlling the display unit, when receiving the call enable notification from the called side in response to the request by the request unit, to display the screen state stored in the memory unit and, when detecting a call instruction in the screen state, an application corresponding to the call instruction to send a call.