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.

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

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

then add country codes for even longer numbers.

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

Up to 14 if you include country codes.

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.

oh wow that's alot

Apparently it’s 7.9 billion combos available

[removed]

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.

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).

Your submission has been removed for the following reason(s):

Loaded questions, and/or ones based on a false premise, are not allowed on ELI5. ELI5 is focuses on objective concepts, and loaded questions and/or ones based on false premises require users to correct the poster before they can begin to explain the concept involved, if one exists.

If you would like this removal reviewed, please read the detailed rules first. **If you believe it was removed erroneously, explain why using this form and we will review your submission.