I’ve been using Google Voice for a while now to record phone interviews for Web copywriting. Usually I’m capturing accurate quotations or how someone talks so I can ghost-write a blog post or first-person bio. You have to have a Google account and get a unique Google Voice number so people can call you (not vice-versa) and Google can alert them when you start recording. The result is a no-frills list of your recordings on your Voicemail page that you can annotate to make an easily readable index. Fast forward and reverse in playback are kinda klunky, but you get used to it.
And Google Voice does a lot more than just record calls.