In order to place a call from one country to another, with your international cell phone, you are required to use country and city codes. Country calling codes help with the processing of data and communications. City codes are used in conjunction with country codes and establish what location in the country the call is coming from. If you are planning a vacation out of the country and are going to purchase a international cell phone it is a good idea to program all the city and country codes you will need into your phone before your departure.

Zip Code Lookup – a zip code lookup system for all states from the United States Postal Service