versaSRS allows a User to be assigned to any number of Queues and Skill Groups. For a User to be assigned Calls in a specific Skill Group (and therefore Queue) they must be Assigned to that Queue:
Note: If you assign a User to a Queue but the User is not assigned to any of the Skill Groups of the Queue, the User will can not be assigned Calls. This allows you to grant a User access to a Queue but not take on the responsibility of a Call Owner.
See also :
Adding a new User
Removing a User from the system
Assigning a User to a Queue
Queue Overview