A portable terminal auxiliary device having a satellite communication function, comprising: a satellite terminal short-range wireless communication module for performing short-range wireless communication with a mobile terminal having a short-range wireless communication module; a satellite radio frequency, RF, module for performing satellite communication through a satellite antenna; a voice data input/output unit for inputting and outputting voice data; and a satellite terminal controller for forming a traffic channel based on satellite communication through the satellite RF module, transmitting voice data received through the voice data input/output unit to the satellite RF module, and outputting the voice data received in the satellite RF module through the voice data input/output unit in response to a request for a voice call from the mobile terminal through the satellite terminal short-range wireless communication module, wherein the satellite terminal short-range wireless communication module, the satellite RF module, the voice data input/output unit and the satellite terminal controller are included in a satellite terminal, the satellite terminal further comprises an urgent call key for requesting an urgent call, wherein the satellite terminal is arranged to store a phone number for an urgent call received by the satellite terminal transferred through the short-range wireless communication module of the mobile terminal, and to place a satellite call by the satellite terminal controller at such a previously stored phone number to transmit and receive voice data when the urgent call key is input, and the satellite terminal is formed with a cradle to mount the mobile terminal on a front side thereof, and the cradle is provided at one side thereof with a holding unit such that a groove formed on one side of the mobile terminal can be coupled and fastened thereto. a satellite terminal short-range wireless communication module for performing short-range wireless communication with a mobile terminal having a short-range wireless communication module; a satellite radio frequency, RF, module for performing satellite communication through a satellite antenna; a voice data input/output unit for inputting and outputting voice data; and a satellite terminal controller for forming a traffic channel based on satellite communication through the satellite RF module, transmitting voice data received through the voice data input/output unit to the satellite RF module, and outputting the voice data received in the satellite RF module through the voice data input/output unit in response to a request for a voice call from the mobile terminal through the satellite terminal short-range wireless communication module, wherein the satellite terminal short-range wireless communication module, the satellite RF module, the voice data input/output unit and the satellite terminal controller are included in a satellite terminal, the satellite terminal further comprises an urgent call key for requesting an urgent call, wherein the satellite terminal is arranged to store a phone number for an urgent call received by the satellite terminal transferred through the short-range wireless communication module of the mobile terminal, and to place a satellite call by the satellite terminal controller at such a previously stored phone number to transmit and receive voice data when the urgent call key is input, and the satellite terminal is formed with a cradle to mount the mobile terminal on a front side thereof, and the cradle is provided at one side thereof with a holding unit such that a groove formed on one side of the mobile terminal can be coupled and fastened thereto.