Method for controlling VCC functions in VCC initiated by terminal and terminal and network server thereof

A method for controlling a voice call continuity (VCC) function of a terminal, comprising:

• receiving, by a first network server, a register message from the terminal during a registration operation of the terminal;
• obtaining, by the first network server, subscriber information associated with the terminal;
• determining, by the first network server, whether or not a user of the terminal is a VCC subscriber based on the obtained subscriber information;
• transmitting, by the first network server, the register message if the determining step indicates that the user is a VCC subscriber;
• determining, by the second network server, whether or not VCC capability information is present in the register message;
• and
• transmitting, by the second network server, a query message to the terminal to determine whether or not the terminal is a VCC capable terminal, if the determining step indicates that the VCC capability information is not present in the register message.

A terminal for controlling a voice call continuity (VCC) function, comprising:

• a controller to generate a register message including VCC capability information of the terminal;
• a transmitting unit to transmit the register message including the VCC capability information to the first network server;
• and
• a receiving unit to receive a response message to the register message from the first network server, the response message selectively including the VCC capability information.

A system for controlling a voice call continuity (VCC) function of a terminal, comprising:

• a terminal to transmit a register message to a first network server;
• the first network server to receive the register message, to obtain subscriber information associated with the terminal, to determine whether or not a user of the terminal is a VCC subscriber based on the obtained subscriber information, and to transmit the register message to a second network server if the user is a VCC subscriber;
• and
• the second network server to determine whether or not VCC capability information is present in the register message, and to transmit a query message to the terminal to determine whether or not the terminal is a VCC capable terminal if the VCC capability information is not present in the register message.