The Manvel Telephone System is one of the first full-duplex (two-way) communication Systems, In this type of telephone Network the subscriber has a telephone set, this telephone set consists of a magnetic bell, a Generator, and a hand Set, While the exchange consists of a single board which is known as F-36 Board, In F-36 Board type of telephone system, the subscriber can’t dial the required subscriber number directly, first he calls the operator and then the operator connects them to the required subscriber.
The F-36 Board has two ports, one is connected to the subscriber, while the other one is connected to the exchange end, Each subscriber which is connected to the exchange has a LED on the control panel of the exchange with a female feeder. When a subscriber wants to call someone, first he generates a signal (voltage) through the generator placed inside the subscriber telephone set, this voltage turns ON an LED placed against each subscriber number, The operator in the telephone exchange connects his handset to the calling subscriber and take from him the called party number, then the operator sends AC voltage towards the called subscriber, due to this voltage the called party telephone set ring up and when he picked up the handset the operator connect his to the calling subscriber, this way a connection established between the subscriber.
Characteristics of Manual Telephone Exchanges
- Uses human operators to manually connect calls by plugging cables between sockets
- Developed in the late 1800s with switchboard operators who would answer calls
- Uses metal patch cords to create a temporary circuit between callers
- Incorporates jack sockets or switches to indicate busy lines
- Operators converse with callers to determine who they wish to call
- Requires operators to disconnect calls when completed
- Larger exchanges may have supervisors overseeing multiple operators
- Switches to ring called parties and provide ringing tone back to callers
- Limited capacity and speed in connecting calls manually
Applications of Manual Exchanges
- Early residential phone service prior to automatic exchanges
- Smaller towns and rural areas with minimal subscriber volume
- Temporary field telephone networks for military or construction
- Disaster recovery when automated switches are damaged
- Shipboard telephone systems before modern digital exchanges
- Hotels, offices, or apartment buildings with an in-house manual switchboard
- Transitional system when upgrading from Magneto to automatic phones
- Independent local phone companies in the early 20th century
Early Residential Service
For the first couple of decades of telephone service, nearly all subscribers connected to manual exchanges. Operators would personally connect local calls by plugging patch cords to complete a circuit. Party lines were common to serve multiple households. Bell's early exchanges provided localized calling.
Small Town and Rural Networks
Independent telephone companies relied on manual exchanges well into the 20th century to serve small towns and rural areas. The lower subscriber volume did not justify automatic equipment. Operators got to know customers personally. Party lines and magneto crank phones were common.
Military and Temporary Sites
Manual switchboards were used for field telephones to coordinate military operations prior to mobile radio. Portable versions were hauled to construction sites or disaster areas temporarily. These manual networks were limited but could be deployed rapidly.
Hotels and Apartment Buildings
Many hotels, motels, and apartment buildings had their own in-house telephone switchboard. A hotel operator handled calls between rooms and connected to the outside phone network. This allowed a private branch exchange before PBX systems.
Naval ships and ocean liners used manual telephone exchanges to route calls between locations on board. Sailors or ship's crew served as operators. This preceded modern digital shipboard phone systems. The Titanic had a manual exchange that became vital during the sinking.
As automatic exchanges were deployed, they were often gradually transitioned while still providing manual service. This hybrid operation allowed expanding automated capabilities while manual operation handled overflow calls.
Examples of Manual Telephone exchange
Bell Telephone Exchange
Alexander Graham Bell's first public telephone exchange opened in New Haven, CT in 1878. It served 21 subscribers and was operated by switchboard operators. This launched a telephone service in the US.
Almon Strowger Exchanges
Kansas City undertaker Almon Strowger patented the Strowger switch in 1891 to automate exchanges. But most remained manual operations into the 1920s.
Farmers' lines were often connected to small manual exchanges in rural towns. Party lines and magneto crank phones were common on these systems.
Telephone Operator Profession
By the 1920s over 100,000 women worked as telephone operators, providing an early workplace for women.
Shipboard Exchanges - Manual switchboards connected calls aboard ocean liners and naval ships prior to automated systems. The Titanic had a telephone exchange.
Small Town Networks
Independent phone companies relied on manual exchanges to serve smaller communities. Growth eventually led to automation with common battery switches.
Many early telephones used magnetos to ring the exchange to get operators to connect calls. Crank ringing gradually gave way to central power.
The Bell System maintained manual long-distance service into the 1940s to connect calls between larger automatic exchanges.
Merits of the Manuel Telephone Exchange,
- It is the First full duplex Telephone System
- It has the best sound quality.
- Central battery System.
- Easy to connect to the called party.
- Small & less in weight.
De-Merits of Manvel Telephone Exchange
- In this type of exchange, there is less privacy.
- 24-hour Communication can’t be possible.
- Without a battery can’t work.
- This system is very costly.
- The installation is much more difficult.
Some interesting historical details on early manual telephone exchange implementations:
Operator Training Programs
Phone companies established extensive operator training programs as the profession grew. Operators had to master switchboard equipment, telephone etiquette, and customer service skills. Bell's motto was "accuracy, speed, and politeness."
Originally operators asked for the name of the subscriber being called rather than a phone number. As phone adoption boomed, numbering systems were implemented requiring callers to know numeric exchanges and lines.
Also called share service, party lines allowed multiple households to share a single line and operator connection. Members had their own rings (short, long, double) to distinguish calls. No privacy!
Over 7000 women served as telephone operators for the U.S. Army Signal Corps in WWI. They were dubbed "Hello Girls" and handled millions of calls in France, enduring harsh conditions near the front lines.
Early manually operated telephones like the candlestick had no external power. Turning the magneto crank generated a ringing current to alert the operator, instead of dial tones.
Small-town operators often went home at night. For emergency night calls, callers turned the crank extra long. A night bell summoned the operator back to the exchange.
Operator Assisted Calls
As dial service increased, operators still assisted with toll calls, collect calls, charges to third parties, and requests for information. This gradually faded as switching modernized.