This is a serious question that gets asked more often than you think! How many times have you been somewhere like a hotel, and someone has asked you “Can we please have a contact number for you, in case we need you for anything.” And you have had to check your phone or struggle to remember your number. Understandably this is because few people these days actually dial a number because phone's address books have the number that you’re calling. So we have put together a list of things you can do quickly to find out what your number is.
Method for all phones:
Call a phone from your phone: Simple just dial a phone close by that has a caller ID, and write down or memorize your number.
If you have an Android phone, you can see your number under >Applications > Settings > About phone > Status > My phone number.
Iphone (all versions):
Settings > Phone
Phone > Contacts
This is just some of the way you can work out what your number is, you may still have emails or text message that contain your new number from when it was originally activated as well.
Mention at: Have cell phones become old school?