Basically, City ID shows you what city and state a phone number is calling from, instead of just seeing the area code and wondering. It is a subscription service, so you may want to review your bill and make sure that you're not being billed for the service if you don't want to be. It is a neat little service, and relatively inexpensive, but I know it's not for everyone. On your bill, it will be located in a section about mobile purchases and downloads, if it's there. If you don't want it, you can remove it from your apps folder on the phone (this varies, depending on your device), or by dialing 611 from your phone and a representative should be able to help you too. Have a great day, hope this helps.