Of course it is. I don’t think that there is anywhere where you don’t need an area code anymore.
There are plenty of places where you don’t need an area code for local calls. It’s only large metropolitan areas with overlapping area codes where ten digits are required.
My town has a population of 18,000 and 10 digits are required.
Mine has a population a fifth of that and 10 digits are required as of a year or so ago.
That was true for a while, but ever since they started allowing local prefixes to have middle 0 and 1 digits, and thus the system can’t tell as easily that those first 3 you dialed might not be an area code, those places are growing rarer by the day.
I think even in Montana, with one area code for the entire state, we needed 10-digit dialing.
I think you’re getting prefixes and area codes confused. Up until the mid eighties or early nineties (before my time in telecom), area codes would follow the formula of “NPX” where N equalled the digits 2-9, P equalled the digits 0 & 1, and X was 0-9. Prefixes followed the formula of NXX. That was how the old switches could tell if you were dialing long distance. If the second digit you dialed were a 0 or 1, then it knew you were dialing an area code. I was in college when the Greensboro/Winston-Salem area got the area code of 336, so they must have changed the area code formula around the early nineties. At that time (I think), they started doing area code overlays, so New York City had the area code of 212 and something else, necessitating the need for ten digit dialing there. As cell phones and pagers (remember those?) became more common, the need for more phone numbers grew, so more and more areas started to have area code overlays. Atlanta (having split away from the Georgia area code of 404 in 1994 or 95), had the area code 770 in addition to its new area code of 470.
My employer used to send out quarterly notices of new areas transitioning to ten digit dialing. That tells me that either the entire country is now using ten digit dialing (which is disproven by someone upthread saying they still have seven digit dialing), or that all of our territory now has ten digit dialing. That is more likely, but pretty amazing, since we cover a lot of West Texas as the native phone company, and good gravy, those are some pretty rural areas. I’ve had have techs drive out (literally) two to three hours to some switch sites, just so they can work on equipment that has not been touched an thirty years. The fact that some of the old Nortel switches are still chugging along says something about the reliability of land lines.
(Finally a topic in the XKCD thread that I can provide useful information on… adjacently.)
NXX would allow area code style prefixes. For example, the original area code for all of Connecticut was 203, which fits the NXX mask. I’m skeptical that 203 would have been a valid prefix in Connecticut, or anywhere else for that matter.
Also note that your explanation of your correction of @Ponderoid is the same thing they said in the first place.
I meant what i said about local prefixes. At one time, the second digit in a local prefix was forbidden to be a 0 or 1, because that was the area code format. That restriction is no longer true. Even with extra area codes, they were running short of local numbers and they started having local prefixes that looked just like older area codes. The moment local numbers start being assigned in an area code which have a 0 or 1 in that position, that region MUST enforce 10-digit dialing for all numbers. If you start dialing a number on a POTS line, and your second digit you dial is a 0 or 1, your call won’t go through until you finish dialing all 10 digits. 7-digit numbers can’t work anymore there.
You are 100% correct. I misread what you’d written.
This is also correct. I had started in telecom in 1999, so the entirety of my recollections of the halcyon days of the pre-Telecom Reform Act of 1996 are due to whiteboard diagrams from my first manager, trying to get me up to speed. For me the formula has always been NPA-NXX, There was a pre NXX formula that I remember seeing in some old Bellcore manuals, but damn if I remember what it was.
Maybe the middle digit of the area code being a 0 if it covered the entire state and 1 if it did not? (Arizona = 602, Los Angeles = 213) I can’t see how that would matter to the switches, though.
Also, if the switch could figure out the first three were an AC because the second digit was 0 or 1, what was the reason dialing 1 to get an out of the area code line being all the rage before ten-digit dialing became common?
I was under the impression that the last of the 7 digit dialing went away when the new national suicide 3 digit hotline went in, but apparently there are still a few holdouts.
The leading 1 meant long distance, and not all out of area code calls were long distance.
And conversely, not all calls within the same area code were at the flat local rate. It’s been ages now, but I remember needing to dial a 1 and seven digits to call a relatively nearby town. Quite annoying.
Our phone system is a hodge-podge of systems of differing ages and capabilities. They might could have preserved 7-digit dialing and made it work, but it was much simpler to just tell people “10-digit dialing. Get used to it.”
<Ernestine> We’re the phone company. We don’t care. We don’t have to. </Ernestine>
I still use seven digit dialing within my area code.
According to the list in k9bfriender’s link four of the area codes still using seven-digit dialing are ones that I had personal knowledge of. That includes my elderly in-laws.
I’m not looking forward to conversations with them when the change takes place. I’ll also probably be the guy who gets to change the local phone numbers to ten digits for the speed-dial buttons on their home phone and cell phone. 
I always thought it odd that, as late as the '80s, we only needed to dial 5 digits. Not 7, not 4… 5.
So, the bowling alley was 7-3344. Which was short for 437-3344… and is now (517) 437-3344.
Ohs noes! I just doxed a bowling alley!
Can you tell me how to convince the cordless phones on my landline that their call-back and call-this-number-again features now need to dial differently? The change effectively broke that feature on those phones for many calls, because it tries to dial calls that used to be 7 digits as 7 digits.
I also remember five-digit local dialing. I can’t remember when it finally disappeared, though; I had thought it was the 70’s, but maybe it was the 80’s.