I am having a similar issue and was basically told by support that there is nothing they can do.

I have a number that was ported from callvantage where cname was working properly. For a while cname was working properly with Voipo.

Now whoever I call they get a number but private shows up in the display. This is verified by calling a vonage number and a verizon number.

Its worse then that, in that I can't even call on paticular vonange number because they have anonymous call rejection turned on.