Design class to handle calls for support functions
I like the Employee class with the built-in Manager chain.
I think Call class should be "dumb" like the Employee. The methods seem like call processing - what the CallManager should be doing.
Id say part of the "call handing process" is in the CallManager and part of it is in Call class. Broken apart like this it's hard to discern/follow the flow of a call-handling.
Should you implement queues? A queue of Calls to model lots of calls coming in before they can get allocated.
The code has allocation and "isFree" as 2 separate things. This suggests to me that we could have a Employee.CallQueue for allocated calls, then set IsFree = false when he picks up the phone.
Also an Employee.CallQueue of assigned calls. The code suggests that allocation and handling are 2 separate things
In ReceiveAndAllocateCall.FindFreeEmployee() could return null so we need code to handle that. Maybe that when the call goes into a waiting queue.




public class CallManager {
     . . .

    // call processing
    call1.AllocatedTo = FindFreeEmployee();

    // what to do if AllocatedTo is null?

    call1.AllocatedTo.IsFree = false;
    call1.IsHandled = false; 

    // I see `IsHandled` as a `Call` property. It will persist if we 
    // pass it to the manager. As is, `IsHandled` disappears when `HandleCall()` ends and we don't know if the call is handled anymore.

    while (! call1.IsHandled) {
     // Write custom logic to handle the call &amp; set the value of isHandled
     if (! call1.isHandled) {
         if (call1.AllocatedTo.Manager != null) { call1.AllocateTo = AllocateTo.Manager
         }else{ break;}
      }
    } // while

    // if IsHandled == false still, what to do? Hang up and send them a lollypop I guess.



The 1st line, calling FindFreeEmployee() might best be done outside of, or somewhere else in CallManager Imagine a complex process for deciding how to pair calls to employees. Then pass that pair into CallManager, and all call manager does is process the call. - Separation of Responsibilities.