My $.02
I read through the other thread and, as those other posts mention, there always seems to be "a catch" to the suggested solutions. And that's a problem for people like me or Heidi or others who have been doing legal recording of phone conversations. We need the recording technology to be reliable because it is just plain bad business to call somebody back and say, "Sorry, my recording gizmo didn't work right... Can you please give me the interview again and say it the way you said it before?"
My solution about a year ago was to buy a Sony Ericsson W810i. It was the only good, reliable cell phone I could find that would easily and reliably record conversations. Yes, unfortunately, there is a very faint high-pitched beep every 20 seconds while recording. I would prefer not having the beep, but the interviewees know they are being recorded anyway, so having the beep isn't awful. I was unable to find another cell phone (and trust me, I tried) that had the native/built-in conversation recorder.
I'm talking about within the United States. In other countries, you can get this function without the beep every 20 seconds.
I would *MUCH* prefer to be able to do this easily and reliably on the iPhone, so please let me know if someone finds out how to do this.
And, again, as I said, it is important that this function be reliable. It is simply not an option to tell an interviewee that, oops, the recorder isn't working properly and I'll need to hang up and restart or re-install or whatever and then call them back. The person will be polite about this, but then when I call back they will not be available--perhaps ever again. This is a matter of being professional.
So, like I said, I went with the Sony Ericsson W810i. It has never given me the White Screen of Death or whatever. And I plug it into my Mac, etc.... I've owned so many Mac desktops and laptops and iPods that I hate not using the iPhone for this, but what else can I do?