A system providing real-time communication over an electronic communication network between two or more users includes a client application associated with each user, a first authentication application having authentication information for at least one user and associated with at least one of the client applications, and a messaging service application maintaining the connection status of all of the users. The first authentication application and the client applications associated with the first authentication application reside on a first private network in communication with a public network. A second authentication application associated with at least one of the client applications and having authentication information for at least one other user reside on a second private network in communication with public network. The authentication applications can receive authentication information from directory services of their private networks. Communication between the authentication applications and the messaging service application is preferably via a secure communications connection.