I am trying to fwd an extension off net to my other offices full int'l number over pstn with cov after fwd'ng set to y, which on my system means for the call to come back to the original extension vm. This is not working. If I fwd this same ext to the internal ext at the remote end, which is qsig.. it still doesn't work. If I use a DCS trunk and fwd this it works the way it should. If I fwd the ext. to a domestic cell phone it works. What can be the issue here?