I just used it in some tests, since I usually don't record phone conversations.I bought this accessory with an Olympus DM-520 just because it was so cheap that I thought it was better having it for some need than miss it in some occasions.I tested it both with conventional and cell phones and the result was very good.I think it is useful to have an opportunity to record, for instance, a conversations when I am complaining about a guarantee or a service. I faced such problem once and I just couldn't proof that the company promised me something that was denied later. Had I recorded those conversations, and I'd had never been cheated by them. Indeed, I have experienced that the only warning that you are recording the conversation changes the way the company ears you.In short: so cheap, so good.