I have a Lumia 920 that I have been using as a wifi only device since I got it, pretty much the month it was released. Recently I put a SIM card in it and as a result I have the volume up now, because I get calls on it. Tonight it started making a strange "notification" sound yet I cannot figure out what it was trying to tell me. No missed calls (and it wasn't the incoming call noise anyway), no new texts, no new emails (and I have "no sound" for when an email comes in), no new Skypes (and I know that sound and it wasn't that), no new anythings according to the live tiles I have pinned.
What can I do, either while the sound is happening or shortly afterwards, to establish what is trying to notify me of something?