Hi all, I am having the following issue: there are 4 phones in a call group. When the first customer calls, all 4 phones ring and someone answers on the first phone. But when the second customer calls, the other 3 phones ring, but not the 4th phone because that person is still on the phone. But when that person hangs up, their phone does not ring, even though the other 3 phones are still ringing. How do I fix this? That person should be able to hang up and then pick up the incoming call.