Difference between queue exits and SLA Overflow

A queue can have several exits that sends the callers elsewhere - to an external number, another queue, a message or a script.

The exits are as follows:

• Empty Exits
  The empty exits are triggered when there are no agents logged on to the queue. 
• Timeout Exits
  The timeout exits are triggered, when the call has reached the maximum amount of seconds/minutes in queue as set in solution. 
• Interrupt Exits
  These are used for interrupting the callers queueing, in order to do something outside of the queue. The interrupt key either transfers them to another queue, external number, a message or to a script.

If a queue in your solution includes all of the above exits or just a few, this is how they will work:

If no agents are logged in yet, or have all logged off for the day, the queue will be considered empty and all the calls will be screened and immediately transferred to the other queue/number or message. 

If there are available agents, but they are all in pause or in calls, the calls will wait in the queue until they have reached the maximum amount of time allowed whereby they will be transferred out of the queue. 

If the queue offers callback options, the callers can of course choose to order a callback but unlike the points above - they will remain in the same queue. 

Thus, in order for the empty exit to work, all agents must log out. If they are in pause the condition will not be met and the callers will remain in that queue until an agent is in a Ready status. 

SLA Overflow does not transfer calls to other queues. The overflow controls the amount of time a call will wait and be offered to a certain group of agents within a queue. 

The groups are determined by the level of skill that they have. The highest skills are 6-9, then 3-5 and lastly, 1-2. The overflow will keep the callers waiting for the highest group to take the calls first and foremost before allocating them to the lower skilled ones. 

In the case that the agents in the highest skill group are all paused, the overflow will not wait for them to change status. Instead, the calls will immediately be allocated to any lower skilled available agent. 

See also System queue settings.

In short, SLA overflow looks for the highest to lowest skilled agents within a queue but will not work as intended if they are paused. 
Empty exit will check if the agents are all logged off before transferring the callers out of the queue.