OK Within the file: conf/directory/default.xml I specifically defined the <domain name="192.168.nn.nn"> to be the 'inside' IP which the SIP phones are to use. And in the conf/sip_profiles/internal.xml I defined sip-ip <== 'inside' IP rtp-ip <== 'inside' IP ext-sip-ip <== 'outside' IP ext-rtp-ip <== 'outside' IP Just in case I also put the same definitions into conf/sip_profiles/external.xml After a FS ReStart I still only see FS_CLI (sofia status) referring to the 'outside' IP And on doing a ReStart of the SIP phone, I still get the same error message as before as seen on FS_CLI Can't find user [105@192.168.nn.nn] from <the phone's IP address> You must define a domain called <FS 'inside' IP address 192.168.nn.nn> in your directory and add a user with the ID '105' attribute and you must configure your device to use the proper domain in its authentication credentials Obviously I am still missing something. Suggestions? Thanks TF