[matthew_b06]

So, I first noticed this issue yesterday when I had my phone on loud + vibrate and it triggered my new IM notification sound but there was nothing new on my phone. I looked in every app, and I had no notifications. I thought it might've been my imagination, but it happened again today. For some reason, my Lumia 920 is playing the notification sound, but I have no new notifications. What the heck is going on? Has this been happening to anyone else?

[WorzelGummage]

Strangely enough yes, the same thing happened with my 920 yesterday. Both my wife and me heard the notification sound but no new notification was to be found anywhere on the phone. Also, I'd sent a friend a message via Facebook chat on the phone about 30 mins prior to this so I assumed he'd replied but there was nothing there.

[Ultimateone]

Could it be an email that is not pinned?

[troylytle]

Games

[poken1151]

like troylytle says, it's probably a game (equally possibly an uinpinned email).

So, what you've stumbled upon is one of the reasons a lot of users still cry for a dedicated notification center (sorry, lil soapbox action in your post). With WP, unless an item is pinned you will not see a notification after the fact. Unless you're staring at the screen as it comes in. Usually this isn't so bad if the app is a well used one... and pinned to your start screen. See, thats the prob, so say you have Skype, AlphaJax, or WhatsApp. Unless the app is pinned, you may get a vib, may hear a sound, but if you walk over get your phone and don't have it pinned, your app hunting for a bit to find out why.

Now, these are apps that support the live tile notifications. Some don't. So, when we look at games like Words With Friends (yea, kinda like they were forced to do it anyway), you can even have it pinned, but if you miss the toast notification and come back, the tile won't even let you know. I do love my WP, but like Android when it first came out, MS still has a lot to do on it.

Anyhoo, keep these things in mind as you go forward, pin a lot of stuff, and remind MS to make it better. Take the toasts that already are supported by default, and let them sit in a window till used. Something. Anything.

[WorzelGummage]

In my case it wasn't an unpinned email or a game. So it's still a bit of a mystery for me

[congusano]

could be any single notification from any single app that you have.

Twitter? I hear it all the time, but unless I have my phone open and in my hand, I miss the toast notification and there is no other possible way for me to know what the notification was unless I check my email and match the email from twitter with the time I heard the notification.

[miodrage]

If u have some battery monitor app, and the battery starts to discharge fast and if set, the app can notify u about that. Or if the battery is low (depending on the threshhold).
Happened to me several times but its either the battery app, or some other app like AppDeals or myAppFree... frankly - I don't give a damn, ain't something of life importance thats for sure.

[chiron09]

My phone does that sometimes as well and its usually an app that is pushing notification like AppDeals, Gtalk Metro, CNN, ESPN etc. The live tile doesn't show anything and that is one my biggest annoyances with Windows phone 8. Really need that universal notification center.

[Nalani]

Is this the sound?
Windows Phone 8, NFC Notification Sound!

[Just_Me]

My phone also started doing this the other day too.
I think it was the recent twitter update I installed.

[WorzelGummage]

I've found the culprit on my phone. It was the CNN app notifying me of breaking news articles. I've turned off the notifications now.

[Huime]

which is why I always argue that we need notification center. Not for the real time notification, but a log of what's been happening. But people had been blindly defending MS for missing such an important feat.

[bobsentell]

If it makes you feel better, it's not limited to Windows Phone. My wife's iPad seems to give the notification ring at random even when nothing is notifying us of anything.