If you register a new handset, and you do not assign it to a SIP account, outgoing calls would work, but you will have troubles with incoming calls (604 SIP error).

You could check within the xml provisioning file if you find:


<subscr_sip_ua_subscribed_hs idx="1">0</subscr_sip_ua_subscribed_hs>


To fix this, go into the web interface of the base station and assign a handset to the extension. Enable checkbox and select "Save option" as follows.