# When we needed to dial only seven digits within the same area code, was four digit dialing typically possible if the prefix was the same? **URL:** \ **Category:** Factual Questions\ **Created:** [October 9, 2024, 9:31am UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593 "2024-10-09T09:31:39Z")\ **Posts on this page:** 14\ **Page:** 3
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 16, 2024, 11:14am UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/41 "2024-10-16T11:14:07Z")
> [@wolfpup](#): > > A large company I used to work for had an interesting internal telephone network. Any company phone anywhere in the world could be reached from any other as a local seven-digit number. It was kinda like a global super-Centrex system. If calling from outside the company, you needed to know both the area code and the exchange. Only the last four digits were the same for the outside world. Both US DoD, and my worldwide airline employer had similar internal systems at one time. Typically the first 3 digits identified a facility or region, and the latter 4 the phone within that facility. Both systems are long gone now. DoD has something newer, the airline simply gave up on the idea as pointless in the modern era. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [October 16, 2024, 2:01pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/42 "2024-10-16T14:01:29Z")
One state university I attended belonged to a state wide “free” telephone system. You could call any other state govt number anywhere within the system without going thru AT&T’s regular long distance system. There were govt phone books around. And if there was a suitable exchange in a another city, you could dial into it and the out to any local number in that city. One of my fellow TAs exploited this system to talk to someone for hours late at night without them having to pay long distance fees. Problem is, these calls were logged and this was considered abuse. (The state was still paying and it was for official use only.) They suddenly became an ex-TA. ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 16, 2024, 5:19pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/43 "2024-10-16T17:19:23Z")
> [@LSLGuy](#): > > > [@wolfpup](#): > > > > A large company I used to work for had an interesting internal telephone network. Any company phone anywhere in the world could be reached from any other as a local seven-digit number. It was kinda like a global super-Centrex system. If calling from outside the company, you needed to know both the area code and the exchange. Only the last four digits were the same for the outside world. > > Both US DoD, and my worldwide airline employer had similar internal systems at one time. Typically the first 3 digits identified a facility or region, and the latter 4 the phone within that facility. I’m probably revealing way too much here, but this company also had something that your airline didn’t have at that time (because no one in the world had it) and that even the DoD was just starting to develop – namely a global digital information network. The Canadian division of this company was short-sighted and considered the network just an email service. All employees had email access, but with very limited storage and virtually no access to other network resources. One of my achievements at this company that I fondly look back on was requisitioning a computer system and setting it up as a full-fledged node on the corporate global network, and making all its resources available to the local office. I was able to do this in part because one of the company’s guiding philosophies was (paraphrased) “do whatever the hell you want, as long as it’s useful to the company”. What the DoD was funding under the auspices of the Advanced Research Projects Agency – ARPA – became known as the ARPAnet. It eventually broke out from limited military and academic use and became a public resource. Today we know it as the internet, and it’s no longer even capitalized. That was in essence what this company had pioneered, and earlier than the DoD. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 16, 2024, 5:32pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/44 "2024-10-16T17:32:15Z")
USAF started down the road to worldwide digital networking in 1958 and had a bunch of it in the late 1960s. Yep sixties. > **[Automatic Digital Network](https://en.wikipedia.org/wiki/Automatic_Digital_Network)** > > The Automatic Digital Network System, known as AUTODIN, is a legacy data communications service in the United States Department of Defense. AUTODIN originally consisted of numerous AUTODIN Switching Centers (ASCs) located in the United States and in countries such as England and Japan. > The design of the system, originally named "ComLogNet", began in 1958 by a team of Western Union, RCA and IBM. The customer was the U.S. Air Force and the system's purpose was to improve the speed and reliability... The airline industry had a worldwide quasi-email system in 1969. Running on this backbone. > **[SITA (business services company)](https://en.wikipedia.org/wiki/SITA_(business_services_company))** > > SITA is a multinational information technology company providing IT and telecommunication services to the air transport industry. The company provides its services to around 400 members and 2,500 customers worldwide, which it claims is about 90% of the world's airline business. Around the world, nearly every passenger flight relies on SITA technology. > SITA or Société Internationale de Télécommunications Aéronautiques, was founded in February 1949 by eleven airlines in order to bring about shared... ---
**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\ **Post date:** [October 16, 2024, 5:51pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/45 "2024-10-16T17:51:47Z")
Very primitive, though, and as your own cite says, eventually superseded by the ARPAnet. The system I’m talking about had features not only like FTP, but also direct access to remote file structures as network devices. ETA: One thing the airline industry deserves major credit for in the area of data communications is the innovation of packet-switching. It came about in airline reservations systems long before the advent of X.25. ---
**Author:** ![E-DUB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/e-dub/32/403_2.png) [@E-DUB](https://boards.straightdope.com/u/E-DUB)\ **Post date:** [October 16, 2024, 6:21pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/46 "2024-10-16T18:21:25Z")
Instead of making it mandatory to dial the area code first, effectively giving everybody a 10 digit phone number, couldn’t we have just gone to eight digits, having all existing customers simply add a zero for the eight digit. We wouldn’t have needed new area codes for a long, long time. I had like three area codes over maybe an eight year period, and it was annoying. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [October 16, 2024, 6:34pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/47 "2024-10-16T18:34:08Z")
Arkansas had one Area code (501) until the late 70’s. Then they split the state. Top half 501 and bottom (below Little Rock) 870. They recently created 2 more. We’re up to 4 now. IIRC there was a transition period you could omit the area code when dialing within that area. At some point Ma Bell brought new equipment online and the area code became required. Funny story. I setup my parents Win 95 pc. Somehow I set the phone dialer to always add 1 to the number. My parents got a large phone bill. All the local calls were being billed as long distance. That required a extended call to the phone company. They did waive the local call charges. I quickly changed their pc’s dialer settings. I don’t remember now what I did wrong. I’m old enough to remember when we didn’t dial the prefix within my town. It was 862- for everybody. We dialed the last 4 digits. Then Ma Bell added new prefixs. Everyone had to dial 7 digits. That’s not fun on a rotary dial. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [October 16, 2024, 6:57pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/48 "2024-10-16T18:57:24Z")
correction, we dialed 2-xxxx or 3-xxxx depending on the persons three digit prefix. This was only within town. The full prefix became required later. A lot of people complained. Rotary dials were cumbersome with longer numbers. ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [October 16, 2024, 7:02pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/49 "2024-10-16T19:02:33Z")
^^Same in my rural community up until sometime in the 1980s. The last five numbers would connect you. I don’t recall being able to dial just the last four. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 16, 2024, 8:43pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/50 "2024-10-16T20:43:26Z")
What was done was consistent with the capabilities of the vast infrastructure of old fashioned non-computerized telephone equipment in place at the time. All of which is now long retired with more flexible computers in their place. Retraining the public is _always_ a major obstacle. The idea of adding a suffix of e.g. zero then later spreading that into other values later is in fact one of the proposals for where the USA’s (North America’s actually) phone dialing system goes next. The difference is they’re thinking of going to 4-digit area codes rather than 8-digit subscriber numbers. See here for history of how the system evolved to date: > **[North American Numbering Plan](https://en.wikipedia.org/wiki/North_American_Numbering_Plan)** > > The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the telephone country code 1. Some North American countries, most notably Mexico, do not participate with the NANP. > The concepts of the NANP were devised originally during the 1940s by the American Telephone and Telegraph Company (AT&T) for the Bell System and the independent tele... and here for various plans to expand beyond 3+7 dialing once needed: > **[North American Numbering Plan expansion](https://en.wikipedia.org/wiki/North_American_Numbering_Plan_expansion)** > > The expansion of the North American Numbering Plan (NANP) is the anticipated requirement for providing more telephone numbers to accommodate future needs beyond the pool of ten-digit telephone numbers. Ten-digit telephone numbers have been in use in the United States and Canada in long-distance telephone service since the 1950s. An October 2020 analysis estimated that the numbering plan would not be exhausted until after 2050. > In the 1940s, the American Telephone and Telegraph Company (AT&T) de... ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [October 16, 2024, 8:49pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/51 "2024-10-16T20:49:41Z")
In Lancaster, CA in the '70s and '80s, the prefixes were 942 and 943. You could dial with five digits: 2-#### or 3-####. Palmdale is seven miles away. Its prefix was 947, and you could dial 7-#### in Palmdale. But to call from Lancaster to Palmdale (or vice versa), it was a long-distance call so you had to dial 1 plus the full number. ---
**Author:** ![aceplace57](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aceplace57/32/3500_2.png) [@aceplace57](https://boards.straightdope.com/u/aceplace57)\ **Post date:** [October 16, 2024, 8:51pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/52 "2024-10-16T20:51:29Z")
> [@Earl\_Snake-Hips\_Tucker](#): > > The last five numbers would connect you. I don’t recall being able to dial just the last four. It was five digits for me too. I initially thought we only dialed 4. Had to think about it for a bit to remember. ---
**Author:** ![Mark\_Finn](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Mark\_Finn](https://boards.straightdope.com/u/Mark_Finn)\ **Post date:** [October 17, 2024, 5:24pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/53 "2024-10-17T17:24:55Z")
Australia did a renumbering in the 1990’s. Most numbers in the two largest cities (Sydney and Melbourne) had been 7 digits - preceded by a 2-digit area/state code. An extra “9” was added between the area code and the phone number. Other numbers elsewhere (of varying lengths) were adjusted to this standard 2+8 format. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [October 20, 2024, 11:23pm UTC](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593/54 "2024-10-20T23:23:34Z")
Yes. When I was growing up, if you dialed within the same exchange, you only needed the four digits. I could call my father’s work that way. This didn’t change until 1970. Even better, the town next to us allowed you to call by only giving three digits (or less for the older numbers). Of course, they didn’t have dial phones (many phones didn’t even have a dial – see below); you picked up the phone, got the operator, and gave the three numbers. Eventually they switched to a four-digit number; a leading zero was added. I don’t know if that was before or after they went to seven digits. To call in, you dialed a number to get the town operator and gave the three digits. [Previous page](https://boards.straightdope.com/t/when-we-needed-to-dial-only-seven-digits-within-the-same-area-code-was-four-digit-dialing-typically-possible-if-the-prefix-was-the-same/1008593.md?page=2)