I have a ring group which has 4 extensions, using firstnotonphone. Anytime an extension is off hook, the ring group does not ring the other available extensions, it forwards the call to the “Destination if no answer” choice. It seems to behave the same on ifavailable. Is there a way for the “offhook” to be treated like “in use”?
What is your “Skip Busy Agent” setting set to in the ring group settings?
Do your phones have Call waiting enabled?
I just tested this w/ a P370 and a D65. Took the D65 off hook and rang a ring group that both phones are in. The D65 presented the call visually but didn’t ring. The P370 was the originator.
Call waiting was enabled originally, I disabled it after trying to look into this issue here. I believe I then enabled the skip busy agent. What is the configuration you were successful with so I can try to test again?