Also, a lot of phone service reps are literally not able to end a call. Often, the customer has to do it.
The other good one is cancelling a contract where they ask you to wait and simply keep your line open and don't let you make any calls for the next 20 mins ... always a joy. AFAIK there's no way on our phone system to force an incoming call to terminate.
Since call center employees commonly have the ability to perform call transfers, I can only imagine they have the ability to hang up on calls. Otherwise, I imagine they could simply transfer the call to an invalid extension to "hangup".