Hi, Suppose my SIP domain is xyz.com. When I use my gateway to register SER, I find that the gateway will send a request message to SER with REQUEST/NOTIFY URI sip:xyz.com:5060. SER will reply a 404 Not found to gateway. However, sip:xyz.com:5060 is invalid address as I do not have this user. Valid sip address should be in the form sip:username@xyz.com:5060. How can I solve this problem? Do you have any idea? Thomas