Make sure your domains are properly aliased to the profile otherwise it won’t find the proper profile to send the notify out. I would have to double check but I’m pretty sure you might be missing this element.
Please confirm, my phone registers to 220@xyz.dom.com through a port that is sofia profile external, should I have profile: external and leave 220@xyz.domain.com?
I have it setup as multi-tennant, if that matters.