There is provided a peer-to-peer telephone system comprising a plurality of end-users and a communication structure through which one or more end-users are couplable for communication purposes. The system is distinguished in that the communication structure is substantially de-centralized with regard to communication route switching therein for connecting the one or more end-users. One or more end-users are operable to establish their own communication routes through the structure based on exchange of one or more authorization certificates, namely User Identity Certificates (UIC), to acquire access to the structure. The structure comprises an administration arrangement for issuing said one or more certificates to said one or more end-users.