Phone Number Structure

The first telephone call was made on March 10, 1876 by Alexander Graham Bell. Bell demonstrated he was able to talk using electricity by transmitting a call to his assistant, and the first message transmitted was something like this “Mr. Watson, come here. I want to see you.”

Nowadays communications have evolved and we can use cell phones and computers to communicate efficiently using the phone number system designed to work very efficiently and able to connect us with every country in the world.

Every day we use phone numbers to call friends or to ask for information, inside our country or between different countries, but did you notice that a phone number has a particular structure? What is the function of each code we dial and what they mean?

So let’s start with the country code!

Country Code

The first part is the country code, it identifies the geographic region of each country and it is usually preceded by a “+” sign. For example, “+34” for Spain, “+1” for United States and Canada or “+65” for Singapore. You don’t need to dial it when you are calling a phone number in the same country and this is the first part we dial to call between two different countries.

Area Code

Area codes identify a specific region inside the country such as states or provinces and can be assigned to cover multiple towns. Depending on the size of the region one or more area codes can be assigned in order to increase the service availability.

Telecommunication companies can split area codes to provide more prefixes in the specific region or they can overlay area codes to make additional phone numbers when the existing area codes are not enough.

The area code can contain 1, 2 or 3 digits. Small countries can have codes of 1 or 2 digits because they don’t need a big number of phone lines. Large countries like United States or Canada use 3-digit area codes.


Prefix is the next part after the area code. The prefix provides a more specific location inside the state or province such as a town or small city.

In United States all prefixes ending in 11 (211, 311, 411, 511, 611, 711, 811 and 911) are service codes and they are not allowed. The prefixes 958 and 959 are for Automatic Number Announcement (ANAC) use and they are unavailable to the general public.

Line Number

And finally, the line number is the last one and most specific part of a phone number. A 4-digit code that provides a specific address to route the call.

Each part of a phone number helps the communication system to find other phones and to identify who is calling and who is going to receive the call. This process takes only a few seconds but is extremely efficient.