You can use area code only for the telephone number and by the area code, you can know names of the cities. There are several cities use the same area code. That is why it is difficult to find out the exact name of the city to identify the place. It is also common that the same area code may be used in some other cities in different countries. You do not need to worry if the area code is same for all of the cities or in other countries. You must like to use internet based tools for communication and find area code.
In three countries, I have found the 999 area code to use. This area code is found in North America for non-Geographic location and it is used as General Purpose. For Mexico and China, this area code is found for the general purpose. The 999 area code is found to use in those as regular use for telephone purpose. In Mexico; Chicxulub Pueblo, Conkal, Kanasin and Merida are the cities use 999 area code. Yining is the only city of China uses the 999 area code. There is no any other city found to use the same 999 area code.