I have an extension that can not be called from inside the network or outside the network, each attempt gets a fast busy. I checked the phone and it is registered to the CM. All other lines attached to the phone can be called just fine. When a dialed number analyzer is used on that extension it shows the phone registration as "unknown". I also found that there are more than one boot load for the phone in question. 7961G, and a call manager 6.1 (I think). I will update with full version if needed.