Unlock your iphone, then press "Settings" and then click "General".
Then click on "About"
Scroll down to Version (in the example IOS 5.1.1 Build 9B206).
Go to your Settings. Click About Phone / Device.
Click "Software Info".
The information about your smartphone version is now displayed. (In the example 6.0.1)
The Settings can easily be accessed via the pull down menu from the top of the phone or the “All apps” button on the home screen
Next find the “System” option from the list displayed and tap it.
Then choose the “About” option and tap it.
This will then display the information about the phone. The Software version can be found under the “Device information” (In the example – Windows 10 Mobile)