Ring group object is a feature which allows you to distribute calls to a group of Users, SIP devices, Skype for business accounts or external numbers, in a couple of configurable ring modes. 

In order to include a Ring group into your call flow, you will need to drag a Ring group object from your PBX toolbox, to your PBX call flow. 

Next you will need to configure the Ring group object, click on the settings icon in the bottom right corner of the object.

Name: A description for the ring group.

Internal number: Any four digit number can be used. This will allow the ring group to be called internally for testing purposed etc. 

Call confirm: Enabled the call confirm feature, this is useful when external numbers are being used inside the ring group. A full description will appear on mouse over of the call confirm button. 

Ring mode: Select the ring mode the suits your needs the most. A full description for both modes is located in the bottom of the ring group settings window. 

Add: Will allow you to enter a range of answering devices for the ring group. 

Once you have successfully configured the ring group connect the object into your call flow and test an inbound call. 

Finally don't forget to Apply the Configuration when any changes are made to the Ring Group or associated objects.