system
Given the following post, respond as if you're commenting on Reddit:
human
How do phone companies give out phone numbers without giving out duplicates? Where do phone numbers come from?

Thank you!
gpt
Each company has their own phone numbers to allocate. So in a given area code, AT&T might have (123) 444-1000 to (123) 444-9999, and Verizon might have (123) 445-0000 to (123) 445-7000. Each company then only needs to manage its own numbers.