This is more a shower thought that has started to eat at me. Even with the addition of area codes and country codes, with all the businesses and people with multiple phone lines, how are we not out of available phone numbers? Is this something to even be concerned about or is there a process to retire and recycle unused numbers?

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Because there are more phone numbers than people. With 10 digit phone numbers, that’s 10 billion phone numbers (minus reserved blocks), which is around 30 phone numbers per person.

And yes, we reuse numbers. Even if we didn’t, 10 billion numbers is enough to cover every American that has ever lived during the time period of phone numbers.

Cities have run out in the past – London (the real one) used to have a dialling code of 01 which was then split into 071 and 081 and later to 020 (which was implemented as 020-7 and 020-8) which increases the domain space each time. 020-3 was introduced a few years later, and now 020-4 has appeared on the scene, all using some of the newly created space

They keep adding new digits.

My UK mobile phone number is 11 digits; UK mobile phone numbers always start with 07, so even within that 07 prefix that’s 9 digits… which is a *lot of numbers -* a billion! Enough for everyone in the UK to have 14 mobile phone numbers each. If they started to run out they’d do what they’ve done before and add another digit to the start – it wouldn’t be super-painful now either because so few people need to remember the actual full numbers!

And yes they do recycle the numbers.

Assuming you are referring to the US,

there are 335 USA area code. That leaves out 7 digits, and each digit can contain one of the 10 different numbers (0-9), and each digit is independent from the others. Therefore, the maximum US phone numbers available are :335 X 10^7=3billion and 350 million phone numbers. US population is around 350 million, barely above the 10% of the maximum phone number possibilities. The actual phone numbers being used may be less than the population due to some people not having phone numbers (i.e. babies, young children, inmates, permanently institutionalized patietns, etc).

An area code can hold about 8 million numbers — the 10 million of 7 digits, reduced by certain disallowed number placements.

So let’s say your area code gets full. No problem, they split off a new area code. I know one place in the country that’s been in three area codes in the last 50 years.

Can we run out of area codes? Not likely since we can do almost 8 billion phone numbers in this country alone if we use all area codes. And old numbers are recycled.

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