Symptom:
Customer fails repeatedly to answer a PersonalCallback from UCCE Outbound Dialer

Conditions:
Normal Operation - Call Center Operation Hours are 08:00 - 18:00p

Reg Key PersonalCallbackMaxAttemptsDefault is set to 5.  Outbound Dialer calls Customer at 17:23   CU fails to answer.  Outbound Dialer sets a PersonalCallback for 30 minutes.  Out Bound Dialer calls the CU back at 17:53 CU again fails to answer the call.  Outbound Dialer sets a PersonalCallback for 30 minutes. Out Bound Dialer calls the CU back at 18:23 

*However* All Agents log out at 18:00 as the Call Center is now closed.

Outbound Dialer makes the call at 18:23 but the Dialer is unable to reserve an agent as there are no agents logged in and by default sets a 24 hour call back.  Dialer makes a new call the next day at 18:23 but again the call center is closed.

This loop keeps happening and that customer is never called again.