Okay, I'm having the same problem. However, I've checked the system forwarding flag on this person's extension and it says yes. It has the same system forwarding setting as all other extensions.
I've also found that when I put the phone in DND, and call it's DID number, it rings through. (DND is set for YES in the system forwarding programming).
In troubleshooting this problem, I've setup a test phone on the system, and enabled the same system forwarding settings as all the other phones (copy & paste), and it's also doing the same thing.
As a last resort, I re-booted the system hoping I had fluke problem that a power down would fix. Unfortunately that didn't work either.
It looks like I may have to call tech support.
Please help!!
