1. On the idle screen you'll see all your available lines. To open a new line, you would simply press on a button that says line.
2. Now you have an incoming call
3. You can leave the call ring and open a new line, by just pressing a line button that is not blinking red. Because this would mean that the incoming call is ringing on that line.
4. No just type in the number and press send as you would usually do.