There are three options for the ring strategy:

ROUND ROBIN

This will ring available queue members one at a time. It will only ring Agents who are currently available in the Team (e.g. not on a call, paused, etc...). 

THE LEAST USED (RECENT) 

This will ring the available queue member who has been offered a call least recently until they answer that call. If another call comes in, it will go to the next available queue member who has been provided a call the least recently.

RING ALL

This will ring all available queue members simultaneously until the call is answered. 

SKILLS BASED (*ENTERPRISE ONLY)

Skills-Based Routing (SBR) is an Enterprise feature that matches calls to the best available agent in the shortest amount of time using tags that are assigned to calls and agents.