A private network system includes a PBX to transmit a message to inquire about receipt of fax data to a mobile device if a message notifying that the fax data will be transmitted is received via an external repeater, a receiver to receive the fax data transmitted from an external device if a fax receipt command is input from the mobile device, and a printer server to check information regarding a printer adjacent to the mobile device from among a plurality of printers, and to control the receiver to transmit the fax data to the checked printer. Accordingly, the private network system facilitates providing the fax data to a printer which is, for example, most suitable for receipt of the fax data, using information regarding the position of a fax recipient and printer information, and thus user convenience can be increased.