How To Use IP Phones - More and more businesses are now opting to use IP phones, but how do they actually work? With VoIP soft phones, a line from your computer plugs in to the back of your phone, allowing you to use it as a normal telephone. In fact, visually, there is little difference between a softphone and a regular telephone. The only real difference is in your telephone bill, which will be significantly reduced if you use IP phones.