1. Field of the Invention
The present invention relates to a mobile communication system. More particularly, the present invention relates to an apparatus and a method for providing other Voice over Internet Protocol (VoIP) services (e.g., Skype, Google talk, and the like) using a terminal which supports an IP Multimedia Subsystem (IMS) network.
2. Description of the Related Art
In accordance with rapid advances of the communication technology, a conventional voice service has come to provide a portable terminal with a high-speed data service which enables multimedia services such as e-mail, still images, videos, and the like.
Third (3rd) Generation (3G) mobile communication systems, which support both of the conventional voice service and a packet service, include a Code Division Multiple Access (CDMA) 2000-1x system using a synchronous scheme and a Universal Mobile Telecommunications System (UMTS) using an asynchronous scheme, which are widely known. The 3G mobile communication systems provide the multimedia services to the portable terminal through the interworking between the IMS network and other networks.
A portable terminal that allows interworking between the IMS network and the other networks is a multimode portable terminal that is capable of using the voice data service in a circuit switch network such as the UMTS and a Global System for Mobile communications (GSM), and using the Voice over Internet Protocol (VoIP) services in a Wireless Local Area Network (WLAN) environment.
The most recent IP Multimedia Subsystem (IMS) is the Release 9 standard which is issued by the 3G Partnership Project (3GPP), the standards body of the 3G mobile communication systems.
The IMS is a network for effectively supporting wireless data demands that are rapidly increasing in mobile communication networks and multimedia services while still supporting the existing voice service. The IMS network complies with a Session Initiation Protocol (SIP) for control signals and message deliveries between the network components.
For the IMS service as described above, users can use the IMS service only through a terminal equipped with an IMS client.
This is the basic precondition required by not only the IMS service but also most of the VoIP services. To use the VoIP service such as Skype, the terminal equipped with a client (e.g., Skype client, and the like) corresponding to the service is required. However, to install the client, the terminal must be a high performance terminal, which increases the cost.
This is because the VoIP service, which is based on peer-to-peer communication, requires considerable abilities of the client, unlike the IMS service which is based on the communication between a server and a client.
The peer-to-peer communication service attracts subscribers with its low communication fee, but has to use the high-cost terminal to install the client corresponding to the VoIP service.
The VoIP service for the presence based peer-to-peer communication is subject to the traffic for presence information and thus a large volume of traffic increases battery consumption even though the mobile communication terminal is not connected to the corresponding service.