Don't think it matters. From what he said is it disconnects the blue tooth connection to the phone as soon as you enter the voice recorder.
So doesn't matter if you call the phone or not, the p3 isn't connected to the phone as long as the recorder is active.
Probably done on purpose to prevent recording conversations. Something about possible legalities coming into play if it did allow it and the headaches in court it would all cause. Let alone the havoc it would play on all kinds of relationships, from friends to more.