Provided are a method of automatically converting a phone number while roaming using a mobile communication terminal, and a mobile communication terminal using the method. The mobile communication terminal sets an automatic conversion mode, stores at least one phone number, reads a phone number selected by a user from among the at least one stored phone number, converts the read phone number to be suitable for an international phone system of a visited country for connection to a home country if the set automatic conversion mode is ON upon when a calling command is input, and controls every module of the mobile communication terminal such that a call can be made to the converted phone number.