Best software to record phone calls with?

I'm doing an interview over the phone tomorrow. I need to record it as it's going to be used for a short movie that we are working on at my school. And yes I know it's illegal to record it without the person on the other end of the line's conscent.

3.5mm out of your phone to a 3.5mm mic input on your computer and record the mic input. That is the best thing I can come up with. Maybe there is an app somewhere.

Do the phone call over VIOP (Skype) and just record the audio that way.