Domain in SIP.conf

Not sure if this should be in General Help or Installation if I have it wrong please move.

I normally run plain Vanilla Asterisk but for this project it was decided FreePBX would be a better solution. The system is up & running I can extension to extension, outgoing & incoming calls, but security is high on my agenda. In Vanilla I always put domain=mysip.server.com under the [General] context in sip.conf, this eliminates 99% of the scum trying to hack the box. However I can’t seem to find the solution in FreePBX, I have it currently in /etc/asterisk/sip_custom.conf & the end points can register using it. However in the CLi I still see

[2014-03-20 00:13:22] NOTICE[16716]: chan_sip.c:28003 handle_request_register: Registration from ‘“667” sip:[email protected]:5060’ failed for ‘72.214.246.167:5062’ - Wrong password

Whereas in the vanilla offering the error is ‘Not in Local Domain’

Despite searching extensively I can’t seem to find a decent howto.

Alan…

Scrap that after more reading I found I didn’t have a module loaded