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On the following picture you can see the records of a call sent to call group Wildix1 that requested a call back at some point (Notice the record with EXITWITHKEY and the subsequent record for ENTERQUEUE on the Wildix1-CB queue):
As you can see, the callback was placed on the call group Wildix1-CB. That way all callback calls requested for the original queue (Wildix1) will be grouped on this specific queue (Wildix1-CB). This makes it far easier to tell things such as the number of callback calls per queue.
On the other hand, if there is no queue with suffix -CB, the callback will be placed on the same queue and the resulting data will look like the following (Notice the EXITWITHKEY followed by the same call being ultimately answered by agent John Doe out of the same queue of wildix2):
In the previous picture, the records related to a call sent to call group wildix2 are displayed. As you can see the caller requested a callback, since there is no wildix2-CB queue, the call was placed on the same (original)queue (wildix2).
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