Telephon-line sharing system using smart terminal and method therof

According to one embodiment of the present invention, a telephone line sharing system using a smart terminal comprises: a smart terminal which detects and connects to a wireless network, and in which a telephone line sharing application for telephone calls is installed to be used for telephone calls; an access point which provides a wireless network connection point to the smart terminal; and a call control device which checks whether at least one smart terminal corresponding to a preset extension number connects to the wireless network, manages an identification, an extension number, and a call condition, or terminal information of each smart terminal connected to the wireless network, receives a call signal from the telephone line to acquire an extension number used for connecting a received call and assigned to the line number of the telephone line, searches for a smart terminal corresponding to the extension number, determines whether the searched smart terminal is connected to the wireless network and transmits a call request signal to the smart terminal if the smart terminal is connected to the wireless network and satisfies the preset call condition, relays a received call corresponding to the received call signal if receiving a call connection signal from the smart terminal, and transmits a call sending signal to the telephone line to relay a sending call if receiving the call sending signal from the smart terminal.