Abstract: A network provides users with a simple and secure way of establishing communication sessions with other users or services, running either over IP networks or other networks, e.g., PSTN. In a sense, the network can broker communication services between two or more users (e.g., people) and/or services. A plurality of different clusters of servers is provided, and each of the clusters may be linked together. In certain embodiments, each cluster includes multiple servers. Users are registered within some specific cluster and given a unique system/network ID. In certain embodiments, messages are not sent directly between users, but instead through at least one intermediate routing service (RS) provided on a server of one of the users. Thus, in certain embodiments, a user may hide or mask his/her personal information from other users even when communicating with them. In certain embodiments, a user may establish a communication session with another user without knowledge of the client device (e.g.