- How do callers get transferred? - do you give them an option to press a button, do this happen after a set period of queuing or do you not queue the calls at all if there are no suitably skilled agents in the Ready state?
- What type of reporting will the supervisors be looking at? - historical or real-time?
- What type of UCCX do they have? Standard, Enhanced or Premium?
If the callers are placed in a CSQ then you can use the Dequeue step before transferring the call to the overflow number.
The stock UCCX Historical Report Contact Service Queue Activity Report can report on dequeued calls so that might solve you problem if it is historical reporting that is required.
If it is real time then the RtCSQsSummary database table allows access to callsdequeued per CSQ. It is pretty straightforward to write a web applications to display CSQ stats and you can obviously format/label them in any way that you like.