Here's a little story... I'm a dumb criminal, and I just reached the point where I want to kill my girlfriend who is 300+ miles away. I know that if I am getting a call from her on my cell phone, I will provide an alibi for myself. So I drive the 300+ miles, dispatch my girlfriend, grab her cell phone and call my cell phone. Alibi established(remember, I described myself as a dumb criminal.).
So who answered the boyfriend's cell phone back in the Cities?