Its a sad day, when something as simple as hanging up a call can't be fixed. We are using a Audiocodes MP 118 FXO. I have called and gotten tech support direct from audiocodes. I've paid for support from 3rd parties supporting audiocodes. No one cane seem to fix the disconnect issue. The voice quality is great with audio codes. But their Service is terrible. I just our fxo to hang up when a user from the pstn hangs up, is that too much to ask? The grandstream fxo does it just fine. The problem is , grandstream voice quality is crap, compared to audiocodes fxo. Why does the voip transition have to be so hard??? We are a reseller, and we can't even get a system working well?? That makes no sense. Hey, on the plus side, BLF works pretty well now with the grandstream phones.