Why are there 4 digits at the end of a phone number instead of 3?

Question

Why are there 4 digits at the end of a phone number instead of 3?

Answer 1

There are more number possibilities with having more numbers.

Answer 2

Original phone numbers were only 4 digits, if you were calling someone on the same swich as you, all you had to dial is 4 digits (this is still true in some rural areas).

When calling between areas (switches) you would tell the operator the switch name.  For example my switch is called the benton switch, if someone from another part of town wanted to call me they would tell the operator "I want to call benton 1234".  Later, as phone switches became more automated, most of the switch names were abbreviated, so benton started with the letters "be" which correspond to 23 so it was 231-1234.

So now you could dial 231-1234 to reach me.

Answer 3

That the way we do it in the US

Answer 4

If there were 3 numbers in each segment, then the 2 segments would get confused at times.