I found the phone call credible. I pulled youtube clips to check the voice of Dieter and it sounded the same to me. The supposed voice of Dieter Weisner sounds a bit clearer than the supposed voice of Michael Jackson on the audio clip. I think it sounds funny, but still may be legit. It is quite possible that Michael's channel was cellular and Dieter's was analogue or some variation of that. A codec on one and not on the other or a gsm codec and a g729 or a any combination. The confession just strikes me as plausible.