A method of controlling the codec mode of a convergence internet protocol (IP) network and a terminal using the method are provided. The terminal may include a variable bit-rate/mode codec controller including a channel status measurement and management (CSMM) unit which measures the status of a wireless channel and provides the results of the measuring of the wireless channel status as channel quality information, and which measures the transfer performance of a received packet and provides the results of the measuring of the packet transfer performance as packet measurement parameter information, and a service quality control (SQC) unit which measures the quality of a multimedia service based on the channel quality information and the packet measurement parameter information, provides the results of the measuring of the multimedia service quality as service quality information and determines a codec mode of the terminal or a counterpart terminal communicating with the all-IP terminal based on the service quality information. Therefore, it is possible to improve the quality of multimedia services.