Well I finally made some progress. I have Kamailio 3.1.0 installed on one server and Elastix 2.0.3 installed on another server. The Kamailio server queries Elastix for authentication, and the SIP clients are able to register with Kamailio. However, the clients cannot call each other. Also, extensions added in the Elastix interface cannot authenticate with Kamailio. I have to manually add the users in the Asterisk database using mysql commands to get the authentication to work. I will need to use a GUI for staff to add / delete numbers. Am I way off base here? Kurt Mullen