Yeah, I've made that mistake in the past.
I went with TakeACall Pro - it's not a freebie, and it has an extra step beyond just hitting "record," but it recorded my U.K. call as well as my digital recorder would've on a land line. I've never had a cell phone recorder with this much clarity. I wish I'd had this when I was on the phone with Kim Salmon for an hour and a half last year.