I was messing around with this, because its something I rarely do.
I was only calling myself using my iPhone via my iPad and iMac. The calls seemed to go through fine because I got my voicemail. However "end"ing the call on my iMac and iPad didnt actually end the call. I could even close the app on both but was still getting audio from my voicemail service. I had to goto the phone app on the iPhone and hang up there defeating the purpose of calling from an iMac or iPad.
Regardless, it work for me...albeit not very well.