In my country there are also providers which are provide sip trunk through fiber optic direct to the customer (IP MPLS) and it is IP based.(without registration).
From 3cx perspective that trunk is always "register" (green) and as far as I know 3cx cannot monitor that kind of a trunk.
The easiest way to monitor IP based trunk will be using standard SIP OPTIONS messages but 3cx does not support initial sending SIP OPTIONS, 3CX is only capable to respond to SIP OPTIONS with OK message if other side initially send SIP OPTIONS message
I am considering to accomplish that with some 3rd party tools on linux, like e.g. SIPp, perfectly if 3cx is on Debian, if there is no response from other side to SIP OPTIONS (from whatever reason) that 3rd party tools then can send me an email.
Or we can put this on Ideas section and wait J.
