Remembering miscellaneous details such as mobile numbers can be a tiresome drag, especially for those who lead fast-paced, busy lifestyles or simply have difficulty memorising things. However, remembering your mobile number is no longer entirely necessary; there are now a multitude of ways to retrieve your O2 mobile number without having to make note of a single thing.
Select your mobile's main menu, scroll to "Contacts," then scroll to "My Numbers." Your number will be on this list under the name "My Mobile Number." Make sure your SIM card is in your mobile before you do this.
Call O2 customer service. To retrieve the number that is relevant to your country and O2 pay plan, go to http://www.o2.com. Once you have retrieved the suitable customer care number, call and ask for your mobile number. Make sure you have the password you decided upon when you joined the O2 network at hand and you will be told your phone number within a matter of minutes. You will also be asked your full name.
Dial your home phone directly from the mobile. After a couple of rings, hang up and check your home phone's missed calls. This will instantly provide you with your mobile number. To make sure that your number won't be withheld, scroll into "Call Settings" beforehand and check that your number will not be made private when calling other numbers.