Patent ID: 8412835

Claim:
A method for supporting a session mobility of a terminal that moves from a first communication network to a second communication network, the method comprising: receiving a session invitation message, by a server, from the terminal; analyzing, by the server, information about a media element included in the session invitation message to determine a type of a session update; and transmitting, by the server, a re-invite message to a counterpart entity of the terminal to allow updating a session between the terminal and the counterpart entity, wherein the analyzing of the information about the media element comprises: checking, by the server, whether a Replace header is included in the session invitation message; if the Replace header is included in the session invitation message, checking, by the server, whether an IMPU (IMS Public User Identity) included in the session invitation message is the same as an IMPU included in a previously received session invitation message of the session; if the IMPUs included in the session invitation message and the previously received session invitation message are the same, checking, by the server, whether the information about the media element included in the session invitation message and information about a media element included in the previously received session invitation message are the same, wherein the information about the media element included in each of the session invitation message and the previously received session invitation message indicates a voice media, a non-voice media, or a voice and non-voice media, if the information about the media element included in the session invitation message and the previously received session invitation message are the same and indicate the voice and non-voice media, determining, by the server, the type of the session update as a combined session update; and if the information about the media element included in the session invitation message indicates one of the voice media or the non-voice media, and if the information about the media element included in the previously received session invitation message indicates the voice and non-voice media, determining, by the server, the type of the session update as a split session update, wherein the combined session update is defined as the session including both of the voice media and the non-voice media are maintained in the second communication network, and wherein the split session update is defined as the session including one of the voice media or the non-voice media are maintained in the second communication network.