Tested on Vollaphone:
Jabra Elite 45e in ear BT headset.
Calls work, listening to music/podcasts work, volume up/down works, pause doesn't. (that or i haven't found that yet).
Small update: it seems that, if you listen to music and there's a call coming in, after you hung up, the headset still "thinks" you're calling. I.e. the mic is working, the music keeps playing in the background, but doesn't come back to the front. For now, it seems that rebooting the phone does the trick. That or, stopping the (default) music player and start over again.