If you have just purchased an iPhone, or the device is still fairly new, you may not recall the telephone number that was assigned by your mobile carrier. This is particularly true if you did not port an old phone number. Thankfully, there is a way to check for the telephone number of your iPhone directly on the device itself. You must open the Settings app on the phone and navigate into the Phone settings, and your telephone number will be displayed.
Open the Settings app on your iPhone by tapping it. This app is typically found on the first home screen and it can be distinguished by the image of gray gears.
Look for the "Phone" menu within settings and tap it to access your iPhone phone settings.
Check the very top item of the phone menu, and you should see an entry labeled "My Number" with your telephone number.