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. Larger and more populated states were assigned more than one area code. The entire state of Georgia was assigned 404.

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, using the Atlanta 4A machine. But most of these operators were not fortunate enough to have Keypulsing like the Atlanta operators and had to dial all calls using a rotary dial.

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.

Nationwide Network in 1960

AT&T introduced a structure for toll switching centers in The United States and Canada. The new structure was based on a 4 level hierarchy of toll centers. At the top of the hierarchy, was the Regional Center (Class 1) of which there were 12 in North America. One of these regional centers was known as "Rockdale" and was located in Rockdale County, in Conyers. Atlanta's toll center at 51 Ivy became designated as "Atlanta 1", a Sectional Center (Class 2). The next level would be the Primary Center (Class 3) and then the lowest level Toll Center (Class 4). It was typical for a higher level center to serve also the function of lower levels for its surrounding area. So Atlanta 1 served as the toll center for Atlanta and as the Primary for North Georgia. In South Georgia, Macon was a Class 2 and Thomasville and Waycross were Class 3.


The Rockdale Regional Toll Center


The Rockdale Center opened in June of 1960. It used the 4A Crossbar switching machine, like the Atlanta toll center at 51 Ivy.

The Atlanta Crossbar Tandem and CAMA

To make DDD possible, another type of crossbar switching machine was placed in service 1960 in the 51 Ivy building. This was called the Crossbar Tandem. A tandem office does not directly serve customer lines. It provides trunk-to-trunk switching enabling central offices to reach other offices without having to have direct trunks. A tandem can be used to handle local calls, toll calls, or a combination of both. When the crossbar tandem is switching toll calls, it is performing the same function as the 4A machine introduced earlier.

The crossbar tandem also sometimes provides other services, such as converting pulsing from one type of office to pulsing that is compatible with another. The one installed at 51 Ivy was specifically placed into service to provide CAMA (Centralized Automatic Message Accounting).

AMA (Automatic Message Accounting) refers to the function of automatically capturing and recording the billing information associated with long distance calls. CAMA was one of the methods used for AMA.

Direct dialed calls from Atlanta Step-by-Step offices were connected to the Crossbar Tandem as soon as you dialed the initial "1". After the rest of the number was dialed, a CAMA Operator came on the line and asked for your number. The CAMA equipment then timed and recorded the billing information on paper tape. The tandem then routed the call to an outgoing trunk.

No. 5 Crossbar offices had their own AMA equipment, known as LAMA (Local Automatic Message Accounting) and could identify the calling party's number and complete direct dialed calls without the services of CAMA. Even in places where it was not desirable to have AMA in a small crossbar office, the crossbar equipment could identify the caller and send the number to the CAMA equipment. So calling from crossbar was much nicer and faster.

ANI (Automatic Number Identification) could be added to Step-by-Step offices also but it was expensive. This was not done in most of the Atlanta offices until about 1970.

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.

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 paper toll 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.
Before the "Calling Card" was the "Telephone Credit Card". Before that, "Third Number Billing" was used. To use Third Number Billing, you placed the call through the operator and asked to charge the call to your home or business phone. The operator would sometimes verify the listing of the number you gave to make sure it was listed in your name.

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 deduce from someone's telephone number. The operator could validate the card number by a computation that verified that the letter was correct for the number given. If your card was lost or stolen, your telephone number would have probably had to be changed to change your card number.

The availability of the telephone credit card did not eliminate the use of Third Number billing but it did reduce its use. The early card numbering system was later replaced with the system in use today consisting of the 10 digit telephone number plus 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 business's real telephone number in a list, write up a toll ticket as a collect call, and put the call through. 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.

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. To reach the airline, the customer would dial the local number for their city. A long list of city telephone numbers were printed on ticket envelopes. That number would be terminated in the airline's central reservations office. For example, a customer in Savannah might dial a local number there. 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. As a part of this setup, the airlines had a voice announcement device associated with their Automatic Call Distributor (ACD). This device would verbally announce the name of the caller's city when the reservations agent answered.

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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