Mine is all over the show, always has been though. Some customers show public and private, others show only public, again others will on some phones both, on other phones not. Sometimes it will be the same model phone with different results. Fanvils typically have never shown the private IP address. This was the case with Fusion, and the same with FSPBX.
We have a number of Fusion boxes with NDLB-received-in-nat-reg-contact enabled on the internal profile. Upon reading a bit more, FS recommends to set this on a per customer level where required. Which can be done through extensions>advanced "rewrite port and ip" - which is apparently the same as NDLB-received-in-nat-reg-contact. We do this for some customers who have issues with NAT and in those cases we definitely only see the public ip.
