I have a strange one:
Customer is running 6.1.2
I have a customer that has operators that also have manager's extensions on their phone. When the manager is on the phone(shared line is in use) if the operate places call using a speed dial or directory number by double clicking, the attendant console always uses the shared line to make the call. If the shared line is not in use the call goes out on her primary extension without issue. This Customer had the problem before in an earlier 4.X release and it was fix at some point in a later 4.x release. Seems to be back in 6.1.