A method of signal transmission to be implemented by a control module of an electronic device, the control module including - a first input/output I/O port to be coupled to a first input module, - a second I/O port to be coupled to an output module, - a third input/output I/O port to be coupled to a second input module, - a control unit, - a storage unit coupled to the control unit and having at least one executable program stored therein, and - a user identification unit coupled to the control unit, the output module being one of an electronic card, an electronic card slot to be connected electrically to an electronic card, and a device that supports International Organization for Standardization ISO 7816 specification, the input modules being one of a baseband module, an antenna module and a device that supports ISO 7816/ Universal Asynchronous Receiver/Transmitter (UART) specification, the method including the following steps of: when a flag of an input signal received from the input module using the first I/O port conforms with a corresponding flag in the control module, configuring the control unit to electrically interconnect the first I/O port and the second I/O port such that the input module is able to communicate with the output module; when a multi-channel management instruction indicating the specific channel within the control module is received from the input module via the first I/O port configuring the control unit to open a first specific channel directing to the at least one executable program stored in the storage unit and to temporarily stop transmission within other channels; and when the input signal received from the input module using the first I/O port includes an identity verifying instruction that is for verifying identity of a user of the electronic device, configuring the control unit to allow the user identification unit to communicate with the input module that is coupled to the first I/O port; and when the input signal received from the input module using the first I/O port includes a Java Applet instruction related to the at least one executable program stored in the storage unit, configuring the control unit to execute the java applet program and to communicate with the first, second and third I/O port (31, 32, 33), so as to enable two of the baseband module, the electronic card, the storage unit, the user identification unit, the antenna module and a wireless transmission module to communicate with each other. - a first input/output I/O port to be coupled to a first input module, - a second I/O port to be coupled to an output module, - a third input/output I/O port to be coupled to a second input module, - a control unit, - a storage unit coupled to the control unit and having at least one executable program stored therein, and - a user identification unit coupled to the control unit, when a flag of an input signal received from the input module using the first I/O port conforms with a corresponding flag in the control module, configuring the control unit to electrically interconnect the first I/O port and the second I/O port such that the input module is able to communicate with the output module; when a multi-channel management instruction indicating the specific channel within the control module is received from the input module via the first I/O port configuring the control unit to open a first specific channel directing to the at least one executable program stored in the storage unit and to temporarily stop transmission within other channels; and when the input signal received from the input module using the first I/O port includes an identity verifying instruction that is for verifying identity of a user of the electronic device, configuring the control unit to allow the user identification unit to communicate with the input module that is coupled to the first I/O port; and when the input signal received from the input module using the first I/O port includes a Java Applet instruction related to the at least one executable program stored in the storage unit, configuring the control unit to execute the java applet program and to communicate with the first, second and third I/O port (31, 32, 33), so as to enable two of the baseband module, the electronic card, the storage unit, the user identification unit, the antenna module and a wireless transmission module to communicate with each other.