A ring group is a group of several telephones that can ring simultaneously, or one after the other in a cascade.
You can set it manually and also via an interactive voice server.
You choose the ringing sequence and its numberr of members for each group of items.
In other words, in the same office, you choose the agents who have to answer the different groups of ring tones, you determine your work teams as internal services.
You can also have a different ringing tone on the same phone line depending on the origin of the call (external call or agent call). As a result, you can choose to restrict incoming calls from customers but remain reachable for your collaborators.