When setting the forwarding rules for a ring group, you cannot set another ring group as the destination.
Virtual Office Configuration Manager
Create an auto attendant to forward to the second ring group.
- Create or use an existing 24/7 schedule.
- Create an Auto Attendant that forwards to the second ring group.
Set the forwarding rules desired to forward to the auto attendant.
This is caused by an issue with the indexing of ring groups.