Digital phone service from the cable company means you can't take your digital video with you -- literally. Your phone is attached to your cable connection in your home and you use it in your home - and that is where it stays. Residential VOIP, however, is usually portable. With many plans, you can use your laptop as a digital phone, and make local calls from anywhere. This makes it a lot easier to make calls -- and even answer your phone or return calls from anywhere.