Vibration every hour, iPhone 4S

[iphone5vibrate]

Hello

I have bought the new iPhone 4S a few days ago and overall I am very satisfied, but 1 thing

My phone vibrates every hour (every oclocks, ie. 1:00, 2:00, 3:00.....) for like 0.5 seconds

when it is on silent, it only vibrates. when it is not, it also makes a funny sound

When this happens, the screen does not light up, and there is no new notification of any of the apps.

I have been trying for the past 24 hours trying to figure out how to disable this, as I concluded that this isn't a bug or broken because it happens with a pattern.


Please help me T.T it is really really annoying me

 

[LBC111]

I also get a more frequent and seemingly random sound "dulloop" which may repeat for several hours and then go away with no text. Very frustrating also because there's no way to determine what it is.

 

[llinc]

check to see if it is your email alerts

 

[LBC111]

No, there is no visual alert associated with it. This is also no change in any incoming data. Nothing related to calendar alerts, emails, messages, timers, etc. I even turned off all notification settings. It no change. A former Apple genius friend said it could be the phone switching off 3G when signal strength is low but I am not convinced.