Abstract: A method for exchanging media description information between user agents using a session initiation protocol (SIP) comprises the steps of: providing information on an OS and sound module of a first user agent so that the first user agent generates, in a media description field of a session description protocol (SDP), an SIP message including the information on the OS and sound module of the first user agent, and sends it to a second user agent; and setting a processing format for voice data of the second user agent so that the second user agent determines the voice data format supportable by the first user agent from the information on the OS and sound module of the first user agent, compares it with the voice data format supportable by the second user agent, and sets a format commonly supportable by the first and second user agents as the voice data format of the second user agent.

Abstract: A method for scaling a display size between different types of user agents. The method includes exchanging session initiation protocol messages including media information when performing a call setup for setting up a media session between the user agents; determining any one of the user agents to scale the display size from the exchanged media information; and scaling, by the determined user agent, the display size on the basis of the media information, and sending video data subject to the scaling to the other user agent(s).

Abstract: An IP based voice/video communication system and call pickup/forwarding method and a program storage device, readable by a machine, tangibly embodying a program of instructions executable by the machine to perform the call pickup/forwarding method enables a subscriber can have voice/video communication irrespective of time or place by forwarding voice/video calls between voice/video communication terminals such as a TV, PDA and home pad, or by picking up a incoming call at a nearby terminal if it is difficult for the subscriber to answer the call at the originally called terminal from his/her location.

Abstract: A method for exchanging media description information between user agents using a session initiation protocol (SIP) comprises the steps of: providing information on an OS and sound module of a first user agent so that the first user agent generates, in a media description field of a session description protocol (SDP), an SIP message including the information on the OS and sound module of the first user agent, and sends it to a second user agent; and setting a processing format for voice data of the second user agent so that the second user agent determines the voice data format supportable by the first user agent from the information on the OS and sound module of the first user agent, compares it with the voice data format supportable by the second user agent, and sets a format commonly supportable by the first and second user agents as the voice data format of the second user agent.

Abstract: A method for scaling a display size between different types of user agents. The method includes exchanging session initiation protocol messages including media information when performing a call setup for setting up a media session between the user agents; determining any one of the user agents to scale the display size from the exchanged media information; and scaling, by the determined user agent, the display size on the basis of the media information, and sending video data subject to the scaling to the other user agent(s).

Abstract: An IP based voice/video communication system and call pickup/forwarding method and a program storage device, readable by a machine, tangibly embodying a program of instructions executable by the machine to perform the call pickup/forwarding method enables a subscriber can have voice/video communication irrespective of time or place by forwarding voice/video calls between voice/video communication terminals such as a TV, PDA and home pad, or by picking up a incoming call at a nearby terminal if it is difficult for the subscriber to answer the call at the originally called terminal from his/her location.