If you need something better than Skype, try a simulrec. Your presenter conducts the interview over the phone but it sounds as though the contributor is in the same room. How's it done? I travel to the contributor and record their end of the interview while you record the interviewer's questions. I send my audio to you straight afterwards and you mix the two halves together. The result can be on air within minutes.

Here's an example. The contributor and presenter were both unable to travel for the interview.