Abstract: Two or more users with PCs or similar devices to access the Internet may establish a connection between each other for instant messaging, even when the users are associated with different realms. For this purpose, the PCs are provided with an IM manager which oversees the instant messaging sessions. In addition, an IM server is provided associated either with a particular SP (service provider), or alternatively, having its own SP. The IM server is used to keep track of all the active users that have registered for the IM service and their corresponding current IP address. The IM manager includes a database which stores protocols of foreign realms. When a user requests an instant messaging session, his PC establishes the connection to the other user based on the protocol of the other user's realm and the other user's current IP address indicated by the IM database.