I just set up google voice to forward my cell calls to my google number yesterday and didn't think to test it yet. Sure enough, whenever I call my cell - from ANY phone - landline or cell.
I found a report form on google forums, but it sounded like people are having problems with their google voice number in general and I am only having problems since I did the forwarding thingy. I get the message: the number you have dialed **my google voice number**, has been changed to a non-published number. I get this message whether I call the google voice number OR my cell phone number from any phone.