# Why haven’t we run out of cellphone numbers?

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In the Netherlands we are close of running out. Around 90% is currently in use and the agency responsible is in the process of releasing a new range of numbers previously used for dialup internet numbers and pagers

The US uses a 10-digit system. Each digit can be any of the 10 numerals in our number system; that means there are 10x10x10x10x10… or 10^10 possible numbers in the US alone. That makes for 10 billion phone numbers possible, for a population of about 350 million. Each person can get over 25 unique phone numbers dedicated to themselves before we run out.

Other countries use different numbers of digits, so there are even more possibilities.

There is also an extra digit or set of digits, known as the country code, that tells the phone which country’s phone system to reach out to. So that gives even more possibilities, as different countries can use the same phone number and rely on the country code to tell the phones apart.

Phone numbers have 10 digits, so there are 10,000,000,000 possible combinations of phone numbers from 000-000-0000 to 999-999-9999. Some of those can’t actually be phone numbers (for example, 911 can’t be an area code, neither can 411, etc.) and area codes can’t start with a 0 or a 1. All in all, there are about 2,030,000,000 unusable numbers, leaving us with 7,970,000,000 usable numbers, which is still a bit more than the world population. Since people can have multiple numbers, we may hit a point where we have to add a digit to expand the available numbers, we’re just not there yet.

(North America) the large part, we just keep adding additional area codes as needed when geographical areas get close to exhausting their supply of available nunbers.

A few days ago a woman called me accidentally and then when I wrote I didn’t know who she was in an ambiguous manner, she called me looking for wisdom from her mother from whom my number was ostensibly derived after reassignment. Not sure of the Dewey Decimal, but I feel this belongs here.