If you don't recognize the last number that called your phone, you may want to find out from where and from whom it came. It can be an advantage to know who you are calling before you return a missed call. In fact, you may choose not to return the call at all. A little research can prevent you from returning a call to a person or place that you don't know.
Enter the number into your cell phone. Once you've put the number in and hit the green button to dial it, the name of the person to whom it belongs will appear on the screen (if the number is stored in your directory). After pressing the green button to dial the number and looking for a name to display, press the red button to stop the call from connecting and to prevent you incurring connection charges.
Narrow down possibilities. The area code of the call will tell you the region or city from which the call came. This will give you a clue to who called you, as you will know if you have any friends or contacts in that area and who they might be. Check in your personal phone or address book to confirm your guesses.
Look the number up on an online reverse phone directory. You will probably find a decent free service for landline numbers, but will probably have to pay for a service that provides information for cell phone numbers. With these services, enter the unknown number into a search box and wait for the name and address of the caller to display.