IPhone 4 won't vibrate in mute mode

So my i have an iPhone 4 and i've had it for about a year now. But like 4 or 5 months ago, i noticed that my phone wasn't vibrating like it used to. For example, i'd switch the mute button on and it says that it's on and the phone vibrates a little when i do that. But i realized that it only vibrated when i text messages and not phone calls. And i usually have my phone on mute, so i'm missing calls like crazy only because it won't alert me and vibrate. For messages its fine. & i've tried the whole settings>sounds>vibrate>vibrate on silent mode thing but it still won't happen. I set my phone back to its factory settings and it still won't work. So i'm not sure what to do and how to fix it. Is there any way or tricks to get it to vibrate when it rings?
please let me know As soon as possible cause i think my warranty expires this week.

You should sync all of the photos and stuff onto iTunes on your computer and get a new iPhone. If you can't get the warranty, if you have the contract with apple you can get the iPhone 4 free

  • Why won't my iPhone 5S let me hear calls and mute my microphone? When I call, they can't hear me and I can't hear them. My microphone won't work with Siri either. Help! And could RadioShack repair it?
  • Why won't my iPhone 4 vibrate when it's locked? Under settings, I already switched "Vibrate on Ring" on and "Vibrate on Silent" on. However, my phone doesn't vibrate when it is switched to silent and the phone is locked. It vibrates if I'm using the phone when I get a text, but not when it is locked. I have ringtones and vibrations set for calls and texts. But nothing happens when it is locked.
  • (UK) Iphone 4 stuck on vibrate mode? I have tried restoring my phone, turning it on and off, checked all the settings and YES switched the thing on the side of the phone. But i can't get it to make a sound, it just vibrates… Anyone know how to restore the sound to my phone?
  • My Iphone won't vibrate when recieving text messages? How to I make my phone vibrate when receiving text messages? I want to be able to have my phone on silent in class but I still want to know when I get a text message. Have the vibration and everything else on. It still doesn't vibrate. I hate this so much! It plays sounds/music but that's it. The volume is up high… Still nothing