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Direct distance dialing (DDD) or direct dial is a telecommunications term for a network-provided service feature in which a call originator may, without operator assistance, call any other user outside the local calling area. DDD requires more digits in the number dialed than are required for calling within the local area or area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called international direct dialing or international direct distance dialing (IDDD).
DDD is a North American Numbering Plan term considered obsolete since completing a call in any manner other than direct dialing became rare. In the United Kingdom and other parts of the Commonwealth of Nations, the equivalent terms are or were "STD", for subscriber trunk dialing, and "ISD" for international subscriber trunk dialing.
[edit] History
The telephone industry made a United States "first" in the New Jersey communities of Englewood and Teaneck with the introduction of what is known now as direct distance dialing. Starting on November 10, 1951, customers of the ENglewood 3, ENglewood 4 and TEaneck 7 exchanges (who could already dial New York City and area) were able to dial 11 cities across the United States, simply by dialing the three-digit area code and the seven digit number (which at the time consisted of the first two letters of the exchange name and five digits).
The 11 cities and their area codes at that time were:
- Boston, Massachusetts (617)
- Chicago, Illinois (312)
- Cleveland, Ohio (216)
- Detroit, Michigan (313)
- Milwaukee, Wisconsin (414)
- Oakland, California (415)
- Philadelphia, Pennsylvania (215)
- Pittsburgh, Pennsylvania (412)
- Providence, Rhode Island (401)
- Sacramento, California (916)
- San Francisco (318) – San Francisco required the special area code 318 for temporary routing requirements[1]
Many other cities could not yet be included as they did not yet have the necessary switching equipment to handle incoming calls automatically on their long-distance calling circuits. Other cities still had either a mixture of local number lengths or were all still six-digit numbers; Montreal and Toronto, Canada, for example, had a mix of six- and seven-digit numbers from 1951 to 1957, and did not have DDD until 1958. Whitehorse, Yukon, had seven-digit numbers from 1965, but the necessary switching equipment was not in place locally until 1972.
[edit] Hardware
The Number 4 Crossbar, or 4XB switch, had been introduced in the 1940s to switch four-wire circuits and replace the incoming operator. With semiautomatic operation analogous to the early days of panel switch, the operator in the originating city used a multifrequency keypad to dial an access code to connect to the correct city and to send the seven digit number to incoming equipment at the terminating city. This design was further refined to serve DDD.
The card sorter of the 4A/CTS (Number 4A Crossbar / Card Translator System) allowed six digit translation of the central office code number dialed by the customer. This determined the proper trunk circuits to use, where separate circuit groups were used for different cities in the same area code, as in the case of Oakland and San Francisco. The new device used metal cards similar in principle to computer punched cards, and they were rapidly scanned as they fell past a light beam. On busy days, it sounded like a machine gun firing.[citation needed] CTS machines were called 4A (Advanced) if the translator was included in the original installation, and 4M (Modified) if it was added later. A 1970s version of 4XB, the 4A/ETS, used a computer to translate. For international dialing, TSPS provided the extra computer power.
The reach of DDD was limited due to the inefficiency and expense of switching equipment, and the limited ability to process records of completed calls. One obstacle was that the majority of switching gear did not provide Automatic Number Identification (ANI). Common control switches such as 1XB switch were fairly quickly retrofitted to provide ANI, and most 5XB switches were initially installed with ANI services. Panel switch were eventually retrofitted, as were some step-by-step that were not scheduled for immediate replacement. Even if a switch had ANI, it could not identify callers on party lines. This was only partly overcome by Tip Party Identification.[2] As the cost of subscriber line carrier declined, party lines were gradually phased out.
As this and other improved technologies became available, as well as Automatic Message Accounting (AMA) computers to process the long distance records into customer bills, the reach of DDD was slow in the 1950s, but quickened in the early 1960s. Electronic switching systems with stored-program capability allowed electronic processing of the dialed digits, referring to electronic memories to determine call routing, and this has reached the state of the art, with digital telephone exchanges which are basically specialized computers that route voice traffic from one "peripheral" to another as digital data. Call routing can now be done based on the area code, central office code and even the first two digits of the line number, although routing based on digits past the central office code is usually limited to cases of competitive local exchange carriers and number portability.
In the 1960s, with the domestic conversion still underway, plans were laid to extend Direct Dialing beyond North America and its nearby islands. With so much new equipment already working that could only handle ten digit phone numbers, a system was devised by which most toll offices did not have to store and forward the whole international phone number. Gateway offices were set up in New York, London and Paris, connected to the ordinary automatic toll network. The New York gateway was at 32 Avenue of the Americas. The new LT1 5XB switch on the tenth floor of 435 West 50th Street received new Originating Registers and Outgoing Senders able to handle 15 digit telephone numbers, with appropriate modifications to Completing Markers and other equipment. Other 5XB in the next few years were installed with IDDD as original equipment, and in the 1970s ESS offices also provided the service.
The key to the new system was two-stage multi-frequency pulsing. The outgoing sender sent its Class 4 toll center an off-hook signal as usual, received a wink as usual as a "proceed to send" signal, and outpulsed only a special 3-digit (later 6-digit) access code. The toll center picked a trunk through the long distance network to the gateway office, which sent a second wink to the originating office, which then sent the whole dialed number. Thus the toll switching system needed no modification except at the gateway. The international trunks used Signaling System No. 5, a "North Atlantic" version of the North American multi-frequency signaling system, with minor modifications including slightly higher digit rate. European MF systems of the time used compelled signaling, which would slow down too much on a long transoceanic connection.
In the 1970s, toll centers were modified by adding TSPS. With these new computers in place, digit storage in the toll system was no longer a problem. End offices were less extensively modified, and sent all their digits in a single stream. TSPS handled the gateway codes and other complexities of toll connections to the gateway office.
- ^ San Francisco and Oakland each had their own separate toll-switches, so calls had to be routed accordingly depending on the final destination. As the telephone equipment used at the time could only handle three-digit translation, the temporary use of area code 318 was required in order to distinguish between the two areas. Area code 318 was temporarily used to specify San Francisco and areas north of the Golden Gate, while calls with destinations in Oakland and the East Bay continued to use area code 415. When the electromechanical card-translator box became available sometime during 1952–53, 6-digit translation became possible and the use of area code 318 was no longer required. Area code 318 was reclaimed for future use and the entire San Francisco Bay Area returned to using area code 415.[1]
- ^ Free Patents Online Tip Party Identification
[edit] References
[edit] External links
 IDDD～International Direct Distance Dialing～ 波ください～ |  Telephone Direct Dialing Long Distance: "The Nation at Your Fingertips" 1951 AT&T 11min more at phones.quickfound.net "How direct long distance dialing made the US a smaller place, and how instantaneous direct communication between Americans without operator assistance became possible." Public domain film from the Library of Congress Prelinger Archive, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and equalization (the resulting sound, though not perfect, is far less noisy than the original). en.wikipedia.org Direct distance dialing (DDD) or direct dial is a telecommunications term for a network-provided service feature in which a call originator may, without operator assistance, call any other user outside the local calling area. DDD requires more digits in the number dialed than are required for calling within the local area or area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called international direct dialing or international direct distance dialing (IDDD). DDD is a North American Numbering Plan term considered obsolete since completing a call in any manner other than direct dialing became rare. In the United Kingdom and other parts of the Commonwealth of Nations, the equivalent terms are or were "STD", for subscriber trunk dialing, and "ISD" for international subscriber trunk dialing. The telephone industry made a United States ... |  Nation At Your Fingertips Bell System film about the first direct distance dialing from Englewood, New Jersey in 1951. |  Long Distance Telephony: "Speeding Speech" circa 1950 AT&T 11min more at phones.quickfound.net "Automation in the telephone industry dispenses with operator long distance dialing to complete calls faster." Public domain film from the Library of Congress Prelinger Archive, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and equalization. en.wikipedia.org In 1892, AT&T built an interconnected long-distance telephone network, which reached from New York to Chicago, the technological limit for non-amplified wiring. Users often did not use their own phone for such connections, but made an appointment to use a special long-distance telephone booth or "silence cabinet" equipped with 4-wire telephones and other advanced technology. The invention of loading coils extended the range to Denver in 1911, again reaching a technological limit. A major research venture and contest led to the development of the audion—originally invented by Lee De Forest and greatly improved by others in the years between 1907 and 1914—which provided the means for telephone signals to reach from coast to coast. Such transcontinental calling was made possible in 1914 but was not showcased until early 1915, as a promotion for the upcoming Panama-Pacific Exposition in San Francisco in the spring of the same year. On 25 January 1915, Alexander Graham Bell ceremonially sent the first transcontinental telephone ... |  Long Distance 1941 AT&T 15min more at phones.quickfound.net Public domain film from the Library of Congress Prelinger Archive, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and equalization. en.wikipedia.org ...In 1892, AT&T built an interconnected long-distance telephone network, which reached from New York to Chicago, the technological limit for non-amplified wiring. Users often did not use their own phone for such connections, but made an appointment to use a special long-distance telephone booth or "silence cabinet" equipped with 4-wire telephones and other advanced technology. The invention of loading coils extended the range to Denver in 1911, again reaching a technological limit. A major research venture and contest led to the development of the audion—originally invented by Lee De Forest and greatly improved by others in the years between 1907 and 1914—which provided the means for telephone signals to reach from coast to coast. Such transcontinental calling was made possible in 1914 but was not showcased until early 1915, as a promotion for the upcoming Panama-Pacific Exposition in San Francisco in the spring of the same year. On 25 January 1915, Alexander Graham Bell ceremonially sent the first transcontinental telephone call from 15 Dey Street in New York City, which was received by his former assistant Thomas A. Watson at 333 ... |  "About Iligan City Part One" City of Iligan,Transportation of Iligan ,People of Iligan city ILIGAN CITY Industrial City of the South Postal Code 9200 Area Code 063 Land Area 775.76sq km Population 225935 Dialects Spoken Cebuano 92.27%, Maranao 3.39%, Tagalog/Hiligaynon 1.00%, others 3.3% Majority can speak and understand Tagalog and English Religion 93.61% Christian, Others 6.39% People and Culture Iliganons are a mixture of the Muslim and Cebuano stock with a bit of Tagalog and some other cultural group minorities and emigrants from other places. Area Profile Iligan City is located at the northwestern coast of Mindanao facing Iligan Bay, 795 kms. south of Manila. It is centrally located in the Visayas-Mindanao domestic market and proximate to the BIMP East AEAN Growth Area. A major component of the Cagayan-Iligan Corridor, the fastest growing regional growth center in Mindanao and one of the priority investment areas in the Philippines. It is the home of the country's steel industry and Mindanao's electric power source. Commerce and Industry Iligan is the industrial, commercial and education center of the province of Lanao del Norte. The city has 14 major manufacturing industries benefiting 6412 semi and highly skilled workers are producing different products such as oxygen and acetylene, pipes and fitting, coco oil, cement, assorted biscuits, caustic soda and polyvinyl chloride, calcium carbide, recapped tires, cold and hot rolled coils, flour and burned and unburned bricks. It is also hosts the ... |  "About Iligan City Part Two" About Iligan City.Beaches,Swimming pool and Spring Water Pool,hospitals,School and And Water Falls of Iligan city. ILIGAN CITY Industrial City of the South Postal Code 9200 Area Code 063 Land Area 775.76sq km Population 225935 Dialects Spoken Cebuano 92.27%, Maranao 3.39%, Tagalog/Hiligaynon 1.00%, others 3.3% Majority can speak and understand Tagalog and English Religion 93.61% Christian, Others 6.39% People and Culture Iliganons are a mixture of the Muslim and Cebuano stock with a bit of Tagalog and some other cultural group minorities and emigrants from other places. Area Profile Iligan City is located at the northwestern coast of Mindanao facing Iligan Bay, 795 kms. south of Manila. It is centrally located in the Visayas-Mindanao domestic market and proximate to the BIMP East AEAN Growth Area. A major component of the Cagayan-Iligan Corridor, the fastest growing regional growth center in Mindanao and one of the priority investment areas in the Philippines. It is the home of the country's steel industry and Mindanao's electric power source. Commerce and Industry Iligan is the industrial, commercial and education center of the province of Lanao del Norte. The city has 14 major manufacturing industries benefiting 6412 semi and highly skilled workers are producing different products such as oxygen and acetylene, pipes and fitting, coco oil, cement, assorted biscuits, caustic soda and polyvinyl chloride, calcium carbide, recapped tires, cold and hot rolled coils, flour and ... |  U_WAVE 待望の2ndアルバム「U_WAVE 2 FRE-QUEN-CY」発売決定！！ 1st ALBUM『U_WAVE』から、約4年ぶりとなる待望の2nd ALBUMが完成！ ドラマ『俺たちは天使だ！ NO ANGEL NO LUCK』のエンディングテーマ曲「Beat call the moment」、Sound HorizonのRevo氏が作詞で参加した「Luna」、新曲4曲を含む全13曲を収録。 ライブで進化、発展し続けているU_WAVEの歴史、そして宇都宮隆とメンバーが紡ぎ出した新たな魅力をすべて凝縮。4年間の進化をこのアルバムでお聞きください！ 【アルバム情報】 価格：¥3150(税込) 品番：MTRES-C1001 発売日：2010年7月14日収録曲： 01:Last Voyage 02:Wave of memories 03:come back to us 04:always 05:My Missing Rose 06:Smoky Woman -another mix- 07:notice 08:ISOLATION 09:12個のkeynote 10:Innocent Cloud 11:Luna 12:Beat call the moment 13:IDDD 〜International Direct Distance Dialing〜 |  DAILY NEWS UPDATE for 03-16 with Dennis Daily Longtime national reporter Dennis Daily scans the news sources for some interesting stuff ... including: Problems at Honda and a "Happy Birthday" for modern-day area codes. | |
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This article incorporates public domain material from the General Services Administration document "Federal Standard 1037C" (in support of MIL-STD-188).
