I have 5 lines. Cox Communications says they are all configured properly and that the lines are configured in a hunt group. When I have 1 person on the phone (1st line) the second caller does not ring to the 3cx/grandstream phones, It just rings and rings till it times out It does not even go to voice mail. If there is someone on line one, then a caller on the next line trying to get in and we get a third caller. The third caller will connect and our phones will ring and if un answered will go to voicemail. I have looked at settings and all look the same? Why wont the second line ring to our system? Any idea what I am missing?