Ask HN: Is there a mobile app that does async voice communication

I have a long conversations with peers that are around different parts of the world so I send them audio clips by recording from my smartphone. The way I've had to do this for now is record voice memos on my android phone ,upload them to Dropbox and then email them over to the recipient. It works, but it's cumbersome. I would have liked to use something like Telegram or WhatsApp messenger to do the same thing as it has less friction in comparison, but that doesn't allow me to mark/save messages for later which is really important. (as with emails I just flag them to come back to them later). It seems like Talko (http://www.talko.com/) is solving this problem but a) these people aren't really on my team (though I could consider them that way) and b) the app is iPhone only. (I'm on Android). Any worth suggestions? I've had a scan down product hunt already.