We have a main server based on Asterisk and we want to make all the users (extensions) to be connected peer to peer through the internet. In other words the server only works to connect the users to each other and provide the peer information (IP address, status, etc.), so once the connection between the peers is completed the server is completely eliminated until the connection is dropped. Our customers will use mainly SIP phones (conventional SIP phones, not necessarily new ones) and also SIP softphones such as X-Lite. Voicemail can be stored in our Asterisk server.