Hi Jordan
You might find this Knowledgebase article useful
https://support.8x8.com/cloud-phone-service/voice/admin-console/work-group-settings/ring-groups/Fast_Busy_When_Forwarding_Calls_from_AA%2F%2FRing_Group_to_an_External_Number
If this doesn't resolve your issue please contact our Support Team and they will be happy to help.