Mobile communication system and method for providing phone number maintaining service

A method for providing a phone number maintaining service capable of allowing a user to continue to use a previously assigned phone number regardless of a change in service provider in a mobile communication system, the method comprising the steps of:

• a) receiving a call request signal with calling terminal information and called terminal information, determining an initial service provider of a called terminal from the called terminal information, and transmitting the call request signal to a communication network formed by the determined initial service provider of the called terminal;
• b) determining a changed service provider of the called terminal based on the called terminal information included in the call request signal, and transmitting the call request signal to a communication network formed by the determined service provider;
• and
• c) transmitting the call request signal transmitted in step b) to the called terminal so that the called terminal can communicate with the calling terminal over a communication network formed by the changed service provider.

A mobile terminal for receiving a phone number maintaining service capable of allowing a user to continue to use a previously assigned phone number regardless of a change in service provider, the terminal comprising:

• a memory for storing NAM (Number Assignment Module) information for receiving the phone number maintaining service;
• a key input module having a plurality of keys, for generating a call request signal input by the user;
• an RF (Radio Frequency) module for transmitting and receiving a call request signal including called terminal information and calling terminal information;
• a display for displaying a phone number of a calling terminal, determined from the received calling terminal information;
• and
• a controller for transmitting the call request signal to a called terminal through the RF module, and upon receiving a call request signal through the RF module, determining a phone number of the calling terminal from the calling terminal information included in the received call request signal.