Area Codes, Part Of The "North American Numbering Plan" Of 1947

[DonRocks]

I don't ever recall having seen a Maryland area code in DC (this may be a cell phone that was used during construction, or a number listed on a permit), so I did a little digging as to how area codes came into existence.

As part of the "North American Numbering Plan" of 1947 - which included 25 countries and territories - a three-digit area code preceded (are you ready for this?) a three-digit "central office code" and a four-digit "station number."

I grew up in a house with the central office code 622, and I remember very well my mom's handwritten telephone directory in which she used two letters and a number - in our neighborhood, 622 was also named "Mayfair 2" and sometimes written as MA2.

If all this sounds like shockingly old history, bear in mind that this plan is from 67 years ago, and 67 years before *that* was 1880. Considering that these numbers are still being used, somebody did something right.

Has anyone here actually made a station-to-station call? I've never known quite what that was; only that they were *expensive*. From what little I remember, there was, in increasing order of expense, direct, collect, and person-to-person - I wonder if I got on my land line right now and dialed zero, if I could still make a person-to-person call (this is where the operator makes the call, and asks the recipient if a specific person is home; if not, you don't get charged and the operator hangs up on both of you).

The breakup of the Bell system (Jan 8, 1982) is something I remember happening, and something I remember being in the news every day and causing lots of chaos, but also something I've never quite understood - I suspect entire dissertations have been written on mere subsets of the subject. What is now Verizon Communications used to be, in some form or another, Bell Atlantic.

[porcupine]

 What is now Verizon Communications used to be, in some form or another, Bell Atlantic.

And before that, C&P (for Chesapeake and Potomac).  feeling old now.

[RWBooneJr]

As part of the "North American Numbering Plan" of 1947 - which included 25 countries and territories - a three-digit area code preceded (are you ready for this?) a three-digit "central office code" and a four-digit "station number."

My job before law school was coding the "new" Bell Atlantic bill, when it went from tiny envelope-sized pages to 8.5"/11". An updated version of the same system is still in use today -- it generates your Verizon bill. As a result of this experience, I know a strangely large amount about phone numbers, nearly all of it boring. Some of the more interesting tidbits:* (1) the original area codes were all small numbers (e.g. 202, 301) to minimize the number of clicks on a rotary phone; (2) the "central office codes" correspond to a physical building that houses the switches that route calls,** a technology which undoubtedly could be replaced now by the computing power in a single smartphone (the central offices are still everywhere -- there's one behind the Exxon at the corner of Lee Highway and Washington Blvd); (3) there are more available numbers in each area code now than there used to be because they reassign them more quickly after they are disconnected (they used to "age" every number for years); and (4) seven digit dialing is still possible within any area code that has no overlay, including DC.

* Yes, these are the more interesting tidbits.

** It doesn't really work this way anymore; they changed how calls are routed to enable you to keep your number when you switch from one carrier to another (this was originally envisioned as occurring between competing local carriers, but then cell phones happened).

[DonRocks]

(1) the original area codes were all small numbers (e.g. 202, 301) to minimize the number of clicks on a rotary phone; (2) the "central office codes" correspond to a physical building that houses the switches that route calls,** a technology which undoubtedly could be replaced now by the computing power in a single smartphone (the central offices are still everywhere -- there's one behind the Exxon at the corner of Lee Highway and Washington Blvd); 

(1) is interesting and makes a lot of sense.

For (2), are you talking about the building near East Falls Church Metro? I have *always* wondered what that building was, even though it has a Verizon sign on it, it made no sense to me. Do people work in there, or does it just house equipment? It's a nice building, but it seems sort of creepy and I've often wondered if it was abandoned.

This brings back a childhood memory. There was supposedly a way to make "free long distance calls" (why do they still charge for long distance calls from a land line - or do they?) The button that hangs up a phone, whatever it's called ... if you clicked it with your finger really fast, say, eight times, it would dial the number "8". And for a period of about a week, we kids would make long distance calls using this method - successfully, I will add - until one day our parents caught us. But I have no idea if they ever showed up on the bill, and I have no idea if this still works.

For example, if a number was 1-202-547-8962, you'd really quickly tap the hang-up button one time, then wait a couple seconds, then tap it two times, then wait a couple seconds, then tap it ten times (for "0"), etc. It absolutely worked, and I have vague recollections of an operator getting on the line and "catching us" doing it - of course we slammed the phone down and ran up to our rooms.

I used to be the master of the prank phone call, and was foolish enough to do it to the operator once. For those of you who don't know, the operator had the power to call you right back - which, when you're a kid, trying not to get caught, scares the crap out of you.

[Al Dente]

So do those central offices serve a purpose anymore? I've always been curious about those empty looking buildings. Seems like a real estate opportunity.

[RWBooneJr]

Don: Tapping the receiver accomplishes exactly the same thing as would dialing a rotary phone, which relies on "clicks" to represent numbers (breaks in the dial tone). So you were just making long distance calls, not free ones. The operator would probably pick up on occasion because you did something that confused the system, so your call was transferred for assistance. Touch tone replaced the clicks in the 60's, but the old system still worked for a long time after that. It may still work, for all I know.

Michael: I believe the central offices are still used as such. My guess is that the switches housed inside have gotten much smaller over time, but demand has increased requiring more equipment at each location. There's also a ton of cable involved, which takes up a lot of space. In any event, I can't recall seeing a new central office being built anywhere, or an old one demolished. You can generally tell a central office because it either doesn't have windows or has windows with nothing behind them (i.e. the "empty looking buildings" you and Don reference). Here is a link to pictures of a few.

[DonRocks]

Don: Tapping the receiver accomplishes exactly the same thing as would dialing a rotary phone, which relies on "clicks" to represent numbers (breaks in the dial tone). So you were just making long distance calls, not free ones. The operator would probably pick up on occasion because you did something that confused the system, so your call was transferred for assistance. Touch tone replaced the clicks in the 60's, but the old system still worked for a long time after that. It may still work, for all I know.

Michael: I believe the central offices are still used as such. My guess is that the switches housed inside have gotten much smaller over time, but demand has increased requiring more equipment at each location. There's also a ton of cable involved, which takes up a lot of space. In any event, I can't recall seeing a new central office being built anywhere, or an old one demolished. You can generally tell a central office because it either doesn't have windows or has windows with nothing behind them (i.e. the "empty looking buildings" your reference). Here is a link to pictures of a few.

But after the first number, there is no dial tone, so there must be something more to it than that. Maybe if you could talk like N!xau it would work just the same.

And ... Oops! on getting charged for those calls - maybe that's how I got caught?

[RWBooneJr]

[Dialing a rotary phone] interrupts the direct electrical current of the telephone line (local loop) a specific number of times for each digit and thereby generates electrical pulses which the telephone exchange decodes into each dialed digit.

See more here and here. Note "tapping" in the latter.

[The Hersch]

(1) the original area codes were all small numbers (e.g. 202, 301) to minimize the number of clicks on a rotary phone;

(3) there are more available numbers in each area code now than there used to be because they reassign them more quickly after they are disconnected (they used to "age" every number for years); and (4) seven digit dialing is still possible within any area code that has no overlay, including DC.

Regarding (1): There's a kernel of truth to this, but obviously while 1 and 2 were small in terms of clicks on a rotary phone, 0 was the very longest digit. I recall hearing that the more important places, like New York, had a 1 in the second position (212), while less important places like Washington DC had a 0 (202). But if you look at an area code map, this doesn't seem to hold up very well (looking at the old area codes).

Regarding (3): One of the biggest changes to the system was the introduction of area codes that don't have a 0 or 1 in the second position. The original area codes all had zeros or ones there, and that's how the switching mechanisms could distinguish an area code from an "exchange". When that changed was when you had to start dialing 1- for long distance, and this also meant that "exchanges" could have a zero or one in their second position, which obviously greatly increased the number of phone numbers available, both with the new area codes and the new exchanges.

I grew up in the JAckson 5 exchange, as it happens (in Arlington, possibly referring to S. Jackson Street, not far from our house). And the phone number I've had for more than 20 years would have been DUpont 7 in the old days (the reference being to Dupont Circle, I assume).

[DonRocks]

Regarding (3): One of the biggest changes to the system was the introduction of area codes that don't have a 0 or 1 in the second position. The original area codes all had zeros or ones there, and that's how the switching mechanisms could distinguish an area code from an "exchange". When that changed was when you had to start dialing 1- for long distance, and this also meant that "exchanges" could have a zero or one in their second position, which obviously greatly increased the number of phone numbers available, both with the new area codes and the new exchanges.

And this must be how you could dial a "local number" using only seven digits (when, exactly, did this cessate?)

What is the difference between an "exchange" and a "central office code?" I'd never heard of a central office code before I looked into this; I always thought the three digits after an area code were simply called an exchange.

Until just now (I'm watching "Night Call," and get your mind out of the gutter ), I had forgotten about "party lines." This is another concept I've never completely understood because I haven't personally experienced it (we had a septic tank for awhile, but when it came to telephony, we were private all the way, [DickVitale]bay-beee![/DickVitale]). This is a pretty easy thing to visualize (picture a single line running between Brownville and Jamesburg), but gosh you'd think the constant ringing would become annoying, and I suppose there weren't many booty calls that took place. I assume that, back in the early days, there were "public phone stations" (not necessarily the phone booths we grew up with) for those who didn't have a telephone in (or a telephone wire running to) their house - this would be similar to having a fountain in the town square for those needing to gather water. I've joked to Matt that he should emblazon the picture of telephone lines into his brain so he can tell his children what they were - kind of like me telling him about payphones (did they *really* disappear in just a couple of decades?!)

[The Hersch]

And this must be how you could dial a "local number" using only seven digits (when, exactly, did this cessate?)

What is the difference between an "exchange" and a "central office code?" I'd never heard of a central office code before I looked into this; I always thought the three digits after an area code were simply called an exchange.

Until just now (I'm watching "Night Call," and get your mind out of the gutter ), I had forgotten about "party lines." This is another concept I've never completely understood because I haven't personally experienced it

You can still dial a "local number" using only seven digits if, as was mentioned above, you are calling from an area with no overlays to the same area, as within Washington DC. (At least with land-lines. I think I have to dial 202 on my mobile, but I make such calls very infrequently.)

Is the difference between an exchange and a central office code the difference between DUpont 7 and just DUpont? A guess.

We never had a party line at home when I was a kid, at least not within my memory, but I do remember in the early 1960s my grandparents had a party line shared with, I think, two other households in the rural Virginia area where they lived. Even at the time, I thought it was really weird. You could tell by the ring pattern if an incoming call was for you, but when you wanted to place a call you had to pick up the receiver to find out if the line was free. If you could hear people having a conversation it wasn't. I don't remember if the etiquette in that situation was just to hang up, or to say "excuse me" and hang up. I think it was probably the former.

[ol_ironstomach]

I clearly remember the GReenbelt 4 on the paper label slipped into the center of our rotary dial phone.  No, Don, switchhook dialing was not how you made long distance calls "for free"...you were simply recreating the electrical action of a rotary dial.  Somebody upthread has already linked the Wiki entry for pulse dialing.  You might also be amused by the tale of how a romantic liaison motivated Strowger, a mortician, to invent the automatic telephone ladder relay in the first place.  And to complete the circle, find the answer to "how did 2600 Magazine get its name?"

DC, MD, and VA were "special" due to a phantom overlay arrangement that lasted until 1991, when number exhaustion (driven in part by a growing number of modem lines) forced the use of exchange codes that were no longer unique across all three jurisdictions.  Maryland also implemented the 301/410 split at that time.  However, I *think* seven-digit dialing was only permitted for intra-LATA calls...for most of us, that meant "DC metro" numbers.  Since I live in the outer 'burbs, when I first picked my house phone number, I used to pay Bell Atlantic a monthly foreign exchange (FX) fee of about $15 for having chosen an exchange code that was nominally assigned to a different CO, one with DC metro dialing privileges.

Amazingly, 1991 was also when the last operator-based switchboard system in the US was retired, in a small town in California.

The thing about the 1/0 middle digit in legacy area codes was that the *sum* of all three digits, being roughly proportional to the total amount of time the rotary dial needed to be in motion, was the thing that decided if a code would be assigned to a more or less "important" area.  Hence, 212 (sum=5 rotary pulses) was the shortest code available under the original system, and went to NYC.  DC 202 (sum=14) was on par with Massachusetts 617 (sum=14).  The original plan didn't require any area code with more than 21 pulses, and you can see how they maintained that even with high first digits by scaling back the third digit.

While the CO is not quite dead yet, Verizon had been doing everything within their power for the past decade to kill the old copper loop model, in part because of deregulation requirements that forced them to provide ultracheap leases on those lines to competitive local exchange carriers (CLECs).  For a while, it was SOP for them to physically sever the copper cables of new FiOS subscribers, to both eliminate the maintenance costs on the old copper plant, and to prevent other providers from selling voice, DSL, or other services over them.  This has been largely mooted by the emergence of VOIP services, and the fact that competitive data speeds now far exceed what those wires could be used for.

[DonRocks]

DC, MD, and VA were "special" due to a phantom overlay arrangement that lasted until 1991, when number exhaustion (driven in part by a growing number of modem lines) forced the use of exchange codes that were no longer unique across all three jurisdictions.  

I hadn't thought about this in over twenty years, but I read this and *immediately* recalled hearing a news story (probably from around 1990) that fax numbers were a major cause of this - the memory was plain as day (it is creepy how the brain works).

I grew up in White Oak, and can definitely remember that I could seven-digit call Rockville but not Gaithersburg (which was "semi-"long-distance - it required a 301 but not a 1, I think), and cost money. but not as much as a call to Cleveland.

[The Hersch]

I seem to recall that back in the dark ages a call from anywhere in the Washington area to Woodbridge VA was a long distance call that was more expensive than calling New York or Boston. I've probably got it wrong.

[DonRocks]

I seem to recall that back in the dark ages a call from anywhere in the Washington area to Woodbridge VA was a long distance call that was more expensive than calling New York or Boston. I've probably got it wrong.

 Don't forget there were three time slots - I vaguely think the cut-off times were 5 PM, 11 PM (when the entire nation got on the phone), and something cruel like 7 AM. Each time slot even had names - maybe something like "prime time," "reduced rate," and "late night" but those are just guesses.

Also don't forget leaving your phone off the hook. That nasty beep you could hear from down the block.