iPhone vibrates out of nowhere

Hey There, Ramon-Ronnie -

Check the settings for vibrate in Sounds and in Notifications. It's possible that you have vibrate turned on for an alert and you aren't aware of it. The resource below will explain in more detail.

Change sounds, ringtones, and alerts on your iPhone, iPad, and iPod touch - Apple Support
http://support.apple.com/en-us/HT204019

Set your iPhone to vibrate

You can set your iPhone to vibrate when you get an incoming call:

1. Go to Settings > Sounds.
2. Turn on Vibrate on Ring and (if you want) Vibrate on Silent.

You can also set vibration patterns for alerts:

1. Go to Settings > Sounds.
2. Select an alert type in the Sounds and Vibrations list.
3. Tap Vibration and select a pattern.

To create a custom vibration pattern, follow these steps:

1. Go to Settings > Sounds.
2. Select an alert type in the Sounds and Vibrations list.
3. Tap Vibration > Create New Vibration.
4. Tap or touch and hold the screen to create a vibration pattern
5. Tap Save and name your vibration pattern.

Last Modified: Feb 5, 2015

Have a great day!

- Judy

I am sure it does not vibrate out of nowhere. In most cases it is when receiving an email or any other notifications.

Like judysings says you can turn that function off in the settings app.

If it does NOT stop it really could be a hardware issue with the mute-switch (device vibrates when switching mode).

Just try out,

Charly