Dear K Ball and Team,
After investigate the issue we found that this is the "Problems with Analog line not hanging up" then what happen here.
When client call-in the AA(Auto Attendant) Script pickup the line then wait for client to press a selection key(If no press will timeout and drop call), then transfer call to specific extension. If whatever, after conversation done, the Call Manager can not detect hangup then the line still exist in the system and will ring again so this need to pickup(Operator may notice silent or busy tone after pickup) and hangup again to confirm hangup.
Technical Explain :-
By default, a analog board terminates a call when it detects a loop current drop.
As we use analog board on a PBX then you may experience an issue where the system does not detect a hangup.
Due to loop current detect sensitivity will un-predictable.
During this we check with Cisco support to tuning the Analog sensitivity.
Best regards,