I use this exam setup when I am traveling:
Basically, both my home and soft-phone ring at the same time and whichever answers first, gets the call.
Another cool thing is that I am able to call my own number and make my home phone ring if I want to speak with my wife.
I use www.voip.ms and created two sub accounts attached to the same number... then I link them by using a group ring. Simple to set up.