Part 3 - Long Distance Advances

The Introduction of Area Codes

In 1947, AT&T introduced the North American Numbering Plan (NANP) for the United States and Canada. 86 codes were assigned. Most states had one area code. The entire state of Georgia was assigned 404. Larger and more populated states were assigned two or more area codes.

Even though Georgia had an area code, switching equipment for placing calls by area code had not made it here yet. So all calls were handled on a manual basis.

1952 - Operator Toll Dialing

In 1952, AT&T introduced "Operator Toll Dialing" to Atlanta. This was made possible by the installation of the new crossbar toll switching machine in the 51 Ivy building.

To connect long distance calls, the 51 Ivy operator simply plugged in to a trunk going into the new machine and keyed the area code and number, much like we do today.

This was referred to as "Keypulsing". The number keys were arranged in two rows with additional keys labeled KP and ST. To place a call to Pennsylvania 6-5000 in New York, for example, the operator would plug a into a 4A trunk and key this..

KP 212 PE6 5000 ST

The keys sent multi-frequency tone signals into the equipment.

At this point in time, the length of a local number varied by city. Atlanta still had 6 digit dialing, using 2 letters and 4 digits, like WAlnut-4636. Bigger cities in the north had 7 digit dialing, made up of 3 letters and 4 numbers like EASton-2475 and the largest cities, like New York had 7 digit dialing, using 2 letters and 5 numbers like TRafalgar 7-5525. Smaller towns might have numbers of only 4 or 5 digits.

AT&T was in the process of standardizing on 7 digits numbers. So a temporary plan was developed to simplify dialing for operators. For operators dialing into places like Atlanta in 1952, where only 6 digits were used, they were instructed to create a 7 digit local number by dialing the first 3 letters of the office name instead of the first two. So calling Atlanta's Walnut office, instead of dialing 404-WA-4636, the operator in another city would need to dial 404-WAL-4636. Smaller towns with 4 or 5 digit numbers could not be dialed by operators until they were given 7 digit numbers.

Operators in smaller towns that switched calls through Atlanta had rotary dials at the switchboard instead of key pulsing but they had the same capability of using operator toll dialing, starting in 1952.

The 4A Crossbar Toll Switching System

The toll switching machine installed in 1952 was known as the Number 4A Crossbar Switching System. This machine was one of many such machines installed throughout North America for toll switching. The first machine of this type had been installed in Philadelphia in 1943. The one installed in Atlanta was a more advanced version. Its original designation was "A4A", which stood for "Anticipated No. 4 Advanced". This was because the new Card Translator system was still being developed. A couple of years later, the card translators were installed and the machine became a "4A".


Crossbar was a type of switching technology that was developed in the 1930s. A number of switching systems were based on this type of switch. The 4A was unique in that it was designed exclusively for switching long distance calls. Card Translators were developed as a way to store the huge number of route translations that were required. The machine also had the ability to try multiple alternate routes if the primary route to a destination city was busy.
The Atlanta 4A machine was connected by trunks with many other 4A machines in other cities and by trunks to most of the local central offices in the state. Calls to Georgia from throughout North America were now routed to the Atlanta 4A and from there to the destination office. In addition to the Atlanta operators, operators in other Georgia cities were able to put calls through the machine.

Operators in Americus, Augusta, Buford, West Point, Columbus, Griffin, LaGrange, McDonough, Milledgeville, Rome, and Savannah were now able to take advantage of Operator Toll Dialing too, dialing through the Atlanta 4A machine.

The Card Translator System

Sometime in the early 1950s, Atlanta's toll machine was upgraded to add the new card translator system.
Using the card translator, a metal card was punched for each 6 digit combination of area code plus office code, with the routing instructions. The translator cards were put into a Translator Box that held about 1000 cards. There were several of these translator boxes installed in the switching office.


The box of cards sat on top of a control unit containing electromagnets that would operate metal bars to select an individual card, causing it to drop down slightly. The holes in the card were read by a light shining through them to a photocell on the other side.

Prior to this system, the switching machine used a system of cross-connected wires to map the routing instructions for each possible area code and office code. It was easy enough to route calls based on the first 3 digits of the number dialed. This could be the local office code for calls completed within the 404 area or would be the area code for other places. To be able to route calls based on another area code plus a local office code in that area (6 digit translation), required more wiring and a Foreign Area Translator for each area code. This is the method that continued to be used in the other crossbar switching systems. But the 4A machine was designed to be a switching point for multiple area codes and sometimes an entire region. So more flexibility was needed.

Multi-Frequency Signaling

The 4A machine brought with it another development, the Multi-Frequency signaling system. This signaling system used tones to pass numbers from one machine to another. While these tones were not the same as Touch Tone, the idea was basically the same.

Prior to the introduction of multi-frequency signaling, machine-to-machine signaling was in the form of dial pulses with Step-by-Step equipment or Revertive Pulse for Panel equipment. Multi-frequency was much faster, allowing calls to be completed more quickly.

Once the nationwide network of 4A machines was in place, multi-frequency signaling was the standard signaling method used for calls across the network. As a caller, you would generally not hear these tones at all, with the exception of calls going through another type of machine called the Crossbar Tandem (XBT). The 4A machines and most other switching machines muted the audio circuit while the tones were being sent.

The Microwave Radio System

Long distance calling was also expanded and improved considerably by the addition of thousands of new circuits. Starting in the 1950s, the Microwave Radio system was developed. This sent thousands of telephone calls as well as radio and television programming between cities, using radio signals beamed between a chain of towers. AT&T Long Lines built the new towers all over North America. Each tower had a group of large horn shaped antennas to focus the signal.

The microwave network greatly increased the number of telephone circuits available between cities. This made it possible to put most long distance calls straight through instead of requiring delayed handling and callbacks.

Special Codes for Operators

Much of North America could now be reached directly by an operator. For most frequently called places and major cities, the originating toll operator had a flip chart with the area code and other routing information. For other places, the operator used the services of a Rate and Route operator who had more detailed information. For places that were still manual and not reachable direct, the originating operator still had to go through an Inward operator in the destination city.

For these and other services, special operator routing codes called TTC (Terminating Toll Center) codes were used. To reach another operator or service, the operator used a regular 4A trunk and keyed the appropriate codes.


A TTC code was assigned to each toll center where operators or facilities were located. These were 3 digit codes, usually starting with "0". The Athens Toll Office, for example, was "043". Within a toll center, 3-digit codes starting with "1" were used to select a specific type of operator or service. For example, "121" was used to reach an Inward operator.

The area code could be omitted if not needed and the TTC code was not used when calling the principle city toll center for a particular area code. Atlanta was the principle city for "404", for example.

The Strike of 1954


On September 29, 1954, telephone workers walked off the job in what turned out to be one of the worst strikes of the century. It lasted almost 8 months.

While most strikers picketed peacefully, there were stories from all over the Southeast about strikers vandalizing Telephone Company facilities. Main cables were cut and sometimes shot at. In Greenville, Tennessee, a bomb destroyed an entire central office building.

1960 - Direct Distance Dialing

In 1960, Direct Distance Dialing (DDD) was introduced, enabling customers to dial long distance calls for the first time.

Prior to the introduction of DDD in Atlanta, the service had been available in many large cities for a number of years. The first trial of customer direct dialing was carried out in 1951 in Englewood, New Jersey. Customers there could dial direct to most major cities. Atlanta was not one of the cities that could be dialed direct during that trial.


With the introduction of DDD, the code "110" was eliminated for reaching a Long Distance Operator and the single digit code "1" was assigned for DDD. The telephone directory explained that you should dial carefully. But if you reached a wrong number, were disconnected or could not get through, you could call your operator and receive credit.

There was a demonstration telephone number printed in the directory that you could call to "try out" direct dialing. The number connected you to a recorded message that was more or less an advertisement for Long Distance, read from a piece of paper by a telephone company employee.

In addition to dialing calls direct, you could still place long distance calls through the operator by dialing "0". At this point, all calls from pay phones and hotel phones still had to be placed through the operator. Direct dialing of those calls came much later. Special billing services, such as person-to-person or collect also required the operator.

To encourage customers to dial station-to-station calls direct, there was a special discount applied. You would not receive this discount if you placed your call through the operator unless you explained that you had tried to dial direct and had difficulty.

The Nationwide Network in 1960

By 1960, AT&T had introduced a structure for toll switching centers in The United States and Canada, based on a 5 level hierarchy of toll centers, designated as Class 1 to Class 4 and local offices designated as Class 5.

At the top of the hierarchy, was the Regional Center (Class 1) of which there were 12 in North America. Under each Regional Center there were between 3 and 7 Sectional centers (Class 2). The Sectional Center usually served a state or a part of a larger state. Under the Sectionals were Primary Centers (Class 3) and then Toll Centers (Class 4). A switching center at a particular level "homed on" a higher level switching center. In many places, the Primary was not used and the Class 4 Toll Centers homed directly on a Sectional Center.

The local central office, serving customers, was designated as Class 5 and usually homed on a Class 4 Toll Center but sometimes homed directly on a higher level toll office, particularly in larger cities.


One of the 12 Regional Centers was known as "Rockdale" and was located in Rockdale County, in Conyers. In 1960, under Rockdale were Sectional Centers: Atlanta, Birmingham, Charlotte, Columbia, Jackson, Jacksonville and Nashville.

Atlanta's original 4A machine at 51 Ivy became a Sectional Center and designated as "Atlanta 1". In addition to serving as the Sectional Center for all of Georgia, Atlanta 1 served as a toll center for Atlanta local offices.

Initially, as can be seen on the map, North Georgia was covered by Toll Centers homing on Atlanta 1. South Georgia had 4 Primary Centers: Macon, Albany, Thomasville and Waycross.

Some years later, Macon was promoted to a Class 2 Sectional Center, homing on Rockdale and Thomasville and Waycross homed on Macon. Albany became a Class 4 Toll Center.


The Rockdale Center opened in June of 1960 in a large building near Conyers. It used the 4A Crossbar switching machine, like the Atlanta toll center at 51 Ivy. The building also housed an AT&T Network Operations Center.

Automatic Message Accounting (AMA)

To make Direct Distance Dialing possible, Automatic Message Accounting (AMA) was introduced. This is the named used for the process of recording the call information for billing purposes. In 1960, this was done using paper tape. An AMA recorder punched holes in the paper tape to record the calling party's number, the number dialed and the start and end times of the call. This paper tape was sent to a billing center for processing.

When DDD began, Atlanta had a mixture of No. 5 Crossbar and Step-by-Step offices. No. 5 Crossbar was originally designed to provide AMA. The only requirement was to add the AMA equipment to the office. The No. 5 Crossbar could also easily identify the calling party's telephone number on private line and 2-party lines. This was known as Automatic Number Identification (ANI). Only party lines having more than 2 parties required the assistance of an operator.

When you dialed a long distance call from the No. 5 Crossbar, the AMA record was made automatically within your central office and the call was sent to the 4A switching machine.

Step-by-Step offices did not have any inherent capability to do billing or Automatic Number Identification. To handle direct dialed calls from Step-by-Step, the Bell System used CAMA.

Centralized Automatic Message Accounting (CAMA)

For Step-by-Step offices and for calls placed from multi-party lines in a a crossbar office, Centralized Automatic Message Accounting (CAMA) was used. When you dialed a call from a Step-by-Step office, your initial digit "1" sent the call to the CAMA office. The CAMA office was a toll switching center with the AMA equipment to record the call details.

Since Automatic Number Identification was not provided by Step-by-Step at the time, an operator had to come on the line and ask you for your number. So after dialing the long distance number, you would hear "Your Number, Please!" and you would give your number to the operator. These were called CAMA Operators. Sometimes there was a delay while you listened to ringing tone until the CAMA operator came on. This was somewhat of a nuisance to customers that placed a lot of long distance calls.

It was theoretically possible to avoid paying for a call by giving the CAMA Operator a wrong number. But there were methods used to prevent this. To investigate billing errors and possible cases of fraud, the telephone company had a Toll Investigation Department and might end up charging the called party for the call. Eventually, in the late 1970s, Automatic Number Identification equipment was added to Step-by-Step offices.

The Atlanta Crossbar Tandem

The 4A machine was a large capacity system designed specifically for long distance switching. To satisfy the need for a smaller system, the Crossbar Tandem was developed. This machine could be used in a local area to switch calls between local offices and could also switch long distance and could provide the CAMA function. To provide CAMA in Atlanta, a Crossbar Tandem was installed in the 51 Ivy building.

Long Distance Billing

Operators during this period still used cord switchboards that were basically unchanged since 1929 except for the addition of the Keypulsing keypads added in 1952. Billing was recorded on hand written tickets and timed through the use of the Calculograph. The calculograph was a timeclock type device that stamped the call start and end times on the back of the toll ticket.

One change that occurred to toll ticketing in the 1960s was the use of automatic optical readers in the accounting office. These readers read darkened circles on the toll tickets that operators filled in. These were similar to the voting ballots and multiple-choice tests used in schools.

If you didn't want to charge the call to the number you were calling from, you could place the call through the operator and ask to make it "collect", which meant that the called party paid. This always involved the operator asking the called party for permission to charge the call to them.

You could also use Third Number Billing, where you gave the operator another telephone number to charge to. Ordinarily, Third Number Billing was used to charge the call to your home or business phone while you were traveling. The operator would sometimes verify the listing of the number you gave to make sure it was listed in your name.

Telephone Credit Cards

The first telephone credit cards were introduced in the mid 1960s. The card numbers consisted of your 7 digit telephone number, your 3 digit billing zone, and a single letter. The billing zone was used instead of the area code. The billing zone for Atlanta was "035". So if your telephone number was 780-2485, your card number might be "780 2458 035 A".

The letter at the end was the only part that you could not easily figure out from someone's telephone number. The operator would validate the card number by a formula that verified that the letter was correct for the number given. This was a crude security system by modern standards. If your card was lost or stolen, your telephone number would have probably had to be changed to give you a new card number.

This early card numbering system was later replaced with the use of your 10 digit telephone number plus a 4 digit PIN number

"Zenith" and "WX" Toll Free Calling

In 1960, there was no 800 toll free service. Business that wanted their customers to be able to reach them free of charge made use of other options. The first of these was known as Zenith. A company would register for the Zenith service and receive a 4 or 5 digit number. They could then advertise the Zenith number in the telephone directory in other cities. Callers could reach them by calling the operator and asking for the Zenith number.

The operator would look up the Zenith number in a book to find the real telephone number of the business. The call would be put through to that number and charged as a regular collect call but without the need to ask permission from the called business.

Another service used "WX" numbers in the same way as Zenith numbers. This service continued until after 800 Service was well established in the late 1960s.

Foreign Exchange (FX) Service

Another common service arrangement at this time was Foreign Exchange (FX) service. Airlines used this to make it easy for their customers to call their central reservations office.

Each airline had a long list of local telephone numbers in various cities. You would see the list of cities and telephone numbers printed on a ticket envelope. To reach the airline, you would dial the local number in whatever city you were in and it would ring the central reservations office.

For example, a caller in Savannah might dial the local Savannah number for Eastern Airlines but the call would actually ring the Atlanta reservations office. To do this, the airline had to lease one or more circuits to each of these cities.

Foreign Exchange Service was also used by businesses that wanted unlimited local calling to another city without incurring long distance charges. A business in Athens, for example, could have an Atlanta line so that they could make calls to Atlanta for a flat rate. This was still expensive, however.

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