I am trying to register an extention with Asterisk. I created a user on the Elastix web pages and entered the user information into the extention under Account1. I have no SIP service with my Grandstream GXP2000. I did not modify any configuration files directly besides the two places listed. I did add the server information, etc, as required. What else must I do to have Account1 register with Asterisk or at least show me where it attempted and can get an error message?