A SIP communication session can be set up between at least two client SIP nodes over at least one proxy SIP node. A proxy SIP node is located based on a destination client name and domain and a secure signal connection is set up between a calling client SIP node and the proxy SIP node. The destination client IP address is located from the proxy SIP node using the destination client name and domain. An additional secure signal connection is set up from the proxy SIP node to a called client SIP node. The secure signal connection and the additional secure signal connection together form a secure signal path. The destination client SIP node is requested to return its IP address across the secure signal path. The returned IP address is used in setting up a data connection between the calling client SIP node and the destination client SIP node.