How Can I Use My Pc to Answer My Voip Phone From the Cable Company ?

I am going to be tele-commuting this summer. I love to listen to music while I work but must also use the landline telephone which is a (voip). How can I use the same headset for both and switch back and forth ? Is there come kind of switch box I could plug the pc and phone into or special headset? I also want to be able to use PC software to dial and recieve calls on my voip. Am I just dreaming here or is there a techie who can help me see the light. HELP!