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moonra_zk t1_j2sizw8 wrote

Reply to comment by redabishai in The Laws of UX - beautiful website explaining 21 rules for effective UX design by Quackerooney

Phone number length is based on how many different numbers you need, that's why they added more digits over time.

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redabishai t1_j2skgje wrote

Of course. I remember in the 90s in New England they started using the area code for local calls.

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foospork t1_j2sr7a2 wrote

IIRC, the phone system was modified in the 90s to allow multiple area codes in one geographic area.

As late as the late 1970s, in some areas, if you were calling a different number in the same exchange, all you had to dial was the last 4 digits. For example, if your number was 555-1212 and you wanted to call 555-1234, all you had to dial was 1234.

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