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How Phone Numbers Work

By March 20, 2019No Comments

The phone numbers you dial, or store in your phone’s contacts app, are essential to making sure your call reaches the right person. Each “chunk” of a phone number has its own meaning, which allows the entire sequence to act like a map, telling your carrier where to direct your call.

Let’s take a look at how phone numbers work, both locally and internationally.

The Parts of a Phone Number

In the United States, phone numbers are made up of 10 digits plus a country code. Therefore, a standard number has this format: +1-xxx-xxx-xxxx.

To help you understand how phones call each other, here’s a breakdown of each part of a phone number:

  • Country code: The country code is the first thing you dial to place a call. Countries around the world have different country codes based on where they’re located. For example, the United States and Canada have the country code +1, while South and Central America have country codes starting with +5.
  • Area code: The area code is made up of the first three digits of a phone number and follows the country code. The area code represents a more specific geographic location and can cover an entire state, several towns, or a fraction of a city, depending on the size of the population.
  • Prefix: The prefix is made up of the second grouping of three digits in the phone number. This number narrows down your call even further, directing it to phones within a certain portion of the area code.
  • Line number: The last four digits make up the line number. You can think of this as your phone’s unique identification number. It’s this final code that sends a call to your specific handset. Incidentally, this means no two phone lines can have the exact same phone number.

What Happens When You Dial a Phone Number

When you dial a phone number, the company connecting your call uses the four parts of the number like an address.

First, they narrow down your call to the country indicated by the country code. Then, they narrow further to the geographic region indicated by the area code and the more specific location indicated by the prefix. Finally, once all this narrowing is done, they send the call directly to your phone using the line number.

If you’re missing any part of the phone number when you dial, the sequence can’t be completed and your call may not connect. However, what happens when you forget the area or country code of your phone call could depend on where you are and who you’re trying to call.

When calling someone with a phone number of the same area code as you, you usually don’t need to dial the country code for the call to work. Similarly, if you’re calling someone with the same prefix as you, you usually don’t need to dial the area code or the country code.

How Cell Phone Numbers Work

Cell phone numbers work just like landline phone numbers. However, unlike landlines, cell phone numbers are assigned based on where the phone was purchased, not necessarily where the phone is now.

It’s important to understand this difference, since it means you can’t assume a person’s location based on their phone number’s area code. In fact, 10 percent of people now have a cell number associated with a different state. This number climbs higher in metropolitan areas.

Now that you know how phone numbers work, you’ll never need to redial again! Just make sure to ask for the area code when someone gives you their number.