Asterisk server setup for P2P call

We have installed the Asterisk server at our server. We would like to use SIP client software to be installed behind the two different Router/NAT server. We would like to configure the Asterisk server to be configured for P2P communication between the SIP client application installed in PC. Initial negotiation would go through the Asterisk server, after the successful session initiation audio/video data should bypass the server and directly transmitted between the Clients.