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TehWildMan_ t1_jaetdvo wrote

North American telephone numbering plan numbers are 10 digits long including a 3 digit area code

Despite some area codes and branch prefixes being reserved, this still provides enough numbers for current needs.

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stevedaher t1_jaev9d0 wrote

Apparently it’s 7.9 billion combos available

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18_USC_47 t1_jaetnx6 wrote

Because it’s not 7 digits… it’s 10 if you count area codes.

Up to 14 if you include country codes.

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TheJeeronian t1_jaeu0uw wrote

Seven digits gives us 10,000,000 possible numbers. Area codes add three more digits, so that's 10 million people max per area code, with 1,000 possible area codes, and an additional 10 country codes.

100,000,000,000 possible codes.

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FrozenKyrie OP t1_jaeu66a wrote

oh wow that's alot

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XsNR t1_jaews2x wrote

Even with that, countries do recycle numbers when they go out of service. Sometimes you'll get texts or calls from people's contacts who previously owned your number.

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a_seventh_knot t1_jaeti10 wrote

because we have area codes that make phone numbers 10 digits.

then add country codes for even longer numbers.

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istubbedallmytoes t1_jaetfxm wrote

Simple. People can(and do) have the same number [prefix and suffix] with different area codes.

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nachiketajoshi t1_jaexluq wrote

There are something like 335 area codes in USA (first 3 digits).

After that, you have 9000000 possible combinations for a 7-digit number. N=1st×2nd×3rd×4th×5th×6th×7th=9×10×10×10×10×10×10=9×106N=9000000

9000000 x 335 = 3,015,000,000, which is roughly 9x the population of USA. And, we have not yet exhausted all the possible the area code (first 3 digits).

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