Computers and Headsets

Is there a way to connect the PC and telephone together so that you can switch from one to the other? My company wants to do CBT training and allow the workers to answer the phone without taking off their headsets. They will be listening to training
on their headset and also be required to anwer their phone. I am not talking about pop-up screens (at least not at this point) but a way to switch from one to the other. I know plantronics has a way, but they require an additional card (ampliphlier) so that it can be done. We would like to do it without having to install additional cards.