Patent ID: 7139827

Claim:
A communication-method notification method for use in a communications system selectively employing different application-layer communication method installed in user information terminals on a network for users to communicate with one another above the network's transport layer at the network's application layer by the different methods, the method comprising: for each user, storing types of the application-layer communication methods operable by users' information terminals; receiving a destination-user designation from a source user requesting communication; based on the stored types of application-layer communication methods, generating a first list describing only application-layer communication methods that are each operable in both the destination user's information terminal and the source user's information terminal; receiving a download condition and an execution condition regarding at least one application-layer communication method present at one, but not both, of a pair of the destination and source user's information terminals in communication with each other, and downloadable to one of the pair not having the communication method present and executable thereon; generating a second list describing the at least one application-layer communication method; and reporting a third list composite of the first list and the second list to the source user before communication begins.