Telephone facts for kids

An old rotary dial telephone

AT&T push button telephone from 1980

A telephone, often called a phone, is a device that lets two or more people talk to each other from far away. It changes sounds, like your voice, into electronic signals. These signals travel through wires or other ways to another phone. That phone then turns the signals back into sound for the person listening. The word "telephone" comes from Greek words meaning "distant voice."

In 1876, Alexander Graham Bell received the first U.S. patent for a device that could clearly send human voices. Many others helped improve this invention. Soon, phones became very important in homes, businesses, and governments.

A phone has two main parts: a microphone (called a transmitter) to speak into, and an earphone (called a receiver) to hear with. These parts are usually together in a handset. You hold this handset to your ear and mouth when you talk. The transmitter changes sound waves into electrical signals. These signals travel through the phone system to the other phone. There, the receiver turns the signals back into sound. Phones let people talk in both directions at the same time.

Most phones also have a way to tell you about an incoming call. This might be a ringer sound or a light. To make a call, you usually use a keypad or dial to enter a telephone number. This number is like an address for the other person's phone. In the very early days, other ways were used to start calls.

The first phones connected directly from one person's home or office to another. This was not practical for many people. Soon, human-operated switchboards took over. These switchboards were then connected, creating a worldwide phone network. Later, radio systems allowed phones to be used in cars and on ships.

Handheld mobile phones for personal use started in 1973. Over time, older analog systems became digital networks. These new networks offered more features and cost less. Today, smartphones are the most common type of phone. They combine mobile computing with phone features.

Modern phones come in many forms. They use different systems like fixed-line (wired), cellular (mobile), satellite, and Internet-based (VoIP). All these systems are part of the global phone network. This means any phone can reach another using its unique phone number.

How the Telephone Was Invented

Alexander Graham Bell's Telephone Patent Drawing

A replica of the telettrofono by Antonio Meucci in Italy

Bell making the first New York to Chicago call in 1892

Before the electric telephone, the word "telephone" meant other inventions. For example, in 1796, Gottfried Huth created a "telephon" using giant speaking tubes. In 1844, Captain John Taylor invented a "telephone" for ships. It used four air horns to talk in foggy weather.

Johann Philipp Reis used the term for his invention around 1860. His device was likely the first to turn sound into electrical signals.

Many people argue about who truly invented the electric telephone. Like with radio or computers, several inventors worked on sending voices over wires. They often improved on each other's ideas. Charles Bourseul, Antonio Meucci, Johann Philipp Reis, Alexander Graham Bell, and Elisha Gray are all linked to the telephone's invention.

Alexander Graham Bell was the first to get a patent for the electric telephone. This happened in March 1876. Before Bell's patent, phones sent sound like a telegraph. This used vibrations and circuits to send electrical pulses. But Bell found that a changing electric current worked best to reproduce sounds. This idea became the basis for his working telephone and his important patent.

In 1876, after Bell's patent, Hungarian engineer Tivadar Puskás suggested the telephone switch. This allowed for telephone exchanges and, later, large phone networks.

Important Dates in Early Phone History

Reis's telephone from around 1861

Bell's first telephone transmitter, shown 50 years later

An ad for an acoustic telephone from 1886

An 1896 telephone from Sweden

A wooden wall telephone with a hand-cranked generator

• 1844: Innocenzo Manzetti first thought of a "speaking telegraph."
• 1854: Charles Bourseul wrote about sending speech electrically.
• 1861: Johann Philipp Reis showed his "Reis telephone." It was the first to send voice using electric signals. He even said, "The horse does not eat cucumber salad."
• 1871: Antonio Meucci filed a patent notice for his "Sound Telegraph." This notice showed he planned to file a patent later.
• 1874: Meucci's patent notice expired.
• 1876 (February 11): Elisha Gray invented a liquid transmitter for the telephone.
• 1876 (February 14): Gray filed a patent notice for sending human voice through a telegraph circuit.
• 1876 (February 14): Alexander Graham Bell applied for his "Improvements in Telegraphy" patent.
• 1876 (March 7): Bell's U.S. patent 174,465 was granted. It covered sending sounds by making electrical changes similar to air vibrations.
• 1876 (March 10): Bell made the first clear speech transmission. He said, "Mr. Watson, come here, I want to see you," and Watson heard him clearly.
• 1877 (April 27): Thomas Edison filed for a patent for his carbon transmitter. This made phones much louder.

How Early Commercial Phones Worked

Early telephones were quite different from each other. Some used water to pick up sound. Others had a metal part that created electricity when it vibrated. Most, however, used the Edison/Berliner carbon transmitter. This made the sound much louder.

At first, phones got their power locally from batteries. Workers had to visit each phone to check its battery. Later, phones were powered by the phone company through the same wires that carried the voice.

The very first phones used only one wire for the connection. They used the ground to complete the electrical circuit. Also, early phones often had only one opening for sound. Users had to listen and then speak (or shout) into the same hole. Sometimes, two phones were used at each end for easier talking.

People soon realized the benefits of phone exchanges. Instead of connecting phones directly, phones were rented in pairs. A person would hire a company to build a line between their home and shop. If they wanted to talk to more places, they needed more phone pairs. Companies like Western Union quickly set up phone exchanges.

To get someone's attention, early users would whistle into the phone. Soon, phones got a bell in a separate box. This bell would ring to announce a call. Later, the rotary dial became common in the 1930s. This allowed people to dial numbers themselves.

In the 1890s, a new, smaller phone came out. It had three parts. The speaker part stood on a stand, looking like a "candlestick." The listening part hung on a hook when not in use. This hook had a switch that connected the phone when you picked it up. Older phones needed a separate switch.

Later, "cradle" designs became popular. These had the speaker and listener combined into one piece, called a handset. This handset rested in a cradle. These were larger than "candlestick" phones.

By the early 1900s, the most popular phone style appeared. It combined the speaker and listener into one molded plastic handle. This handle rested in a cradle on the base unit. In the 1930s, phones started combining the bell and other parts into the desk unit. This meant no more separate bell boxes. After World War II, phone networks grew quickly. New, more efficient phones were made, like the model 500 telephone. A big step forward was the push-button telephone in 1963. These used "Touch-Tone" signals.

• 

  Ericsson DBH 1001 (around 1931), the first phone made with a Bakelite case.

• 

  Telephone used by American soldiers during WWII in the Philippines.

• 

  One type of mobile phone, called a cell phone.

Phones Powered by Sound

A modern emergency telephone that works only with sound power.

A sound-powered telephone sends voice messages through a wire. It gets its power from the energy of the sound waves from the person speaking.

How Sound-Powered Phones Work

A special microphone turns sound waves into an electrical signal. This signal then travels to the other end. There, it is changed back into sound waves by the receiver. Like early regular phones, these phones usually have a hand-cranked generator. This generator makes an electric current that rings a buzzer at the other end. Some systems can use outside power for ringers or amplifiers. But they can still work with sound power if the main power fails. These phones can work over long distances, even several kilometers apart. Some can work up to 48 kilometers (30 miles) apart.

Where Sound-Powered Phones Are Used

A U.S. Navy officer using a sound-powered telephone during a drill.

Sound-powered phones do not need outside electricity. This makes them useful where reliable communication is very important, even if power is lost. They are often used in airports, railways, mines, and on ships. Because they use low voltage, they are safe in places where there is a risk of explosions or fire. This includes chemical plants and oil rigs. On navy ships, they have extra wires to make sure they still work if some are damaged in battle.

Digital Phones and Internet Calling

An IP desktop telephone connected to a computer network.

Fixed telephone lines per 100 people from 1997 to 2007.

The invention of the transistor in 1947 greatly changed phone systems. Over the next few decades, phones slowly became digital. This made the network better, cheaper, and able to handle more calls.

ISDN started in the 1980s. It gave businesses and homes digital phone services. These included data, voice, video, and fax.

New ways to send digital data made it possible to turn voices into data. This data could then be sent over computer networks and the Internet. This led to Internet Protocol (IP) telephony, also known as VoIP. VoIP is quickly replacing older phone systems.

By 2005, many phone users in Japan and South Korea had switched to VoIP. This technology has created a new industry with many companies offering VoIP services. The global VoIP market was worth $85.2 billion in 2021. It is expected to reach $102.5 billion by 2026.

IP telephony uses fast Internet connections. It also uses special equipment to send phone calls over the Internet. This equipment can be an adapter for a regular phone, a special IP Phone, or a computer program. This program uses your computer's microphone and headset.

Recently, VoIP has also started working with mobile networks. This includes Voice over LTE (VoLTE) and Voice over 5G (Vo5G). These allow clear voice calls over mobile data networks. VoIP is now a main way to communicate online and a key part of modern mobile phones.

Older analog phones get power from the phone company through the phone line. Digital phones, however, need their own local power supply. Internet-based digital services also need special ways to tell emergency services your location when you call 911.

Cordless Telephones

A cordless telephone system with a handset on a base station (left) and another on a charger (right).

A cordless telephone has a base station and one or more portable handsets. The base station connects to a phone line or uses VoIP. The handset talks to the base station using radio signals. A handset can only work within a certain distance, usually inside the same building.

Cordless Phone Base Station

The base station has a radio that sends and receives signals from the handsets. It often has a microphone, speaker, and amplifier. This lets you have hands-free conversations without using the handset. The base station might also have a keypad for dialing and a screen for caller ID. Some even have a built-in answering machine.

The cordless handset has a rechargeable battery. The base station recharges this battery when the handset sits in its cradle. Systems with many handsets usually have extra charging stands. A cordless phone needs constant electricity to power its base station and chargers.

Mobile Phones

Two decades of mobile phone evolution, from 1992 to 2014.

A typical SIM card.

A mobile phone, or cellphone, is a handheld phone. It connects to a cellular telephone network using radio signals. This network has ground-based stations with antennas, usually on towers or buildings. These stations connect to the global phone network. Analog cellular networks started in 1979. Digital cellular networks, like GSM, began in the early 1990s. Over time, these networks improved. Each new generation (2G, 3G, 4G, and beyond) offered faster data and more features.

Mobile phones need a SIM card. This small card has a chip that stores your unique ID number. This number helps the cellular network recognize and connect you.

Mobile phones usually have an LCD or OLED screen. Some, like smartphones, have touchscreens. Since the 1990s, mobile phones have gained many features beyond just making calls. These include text messaging, calendars, alarms, cameras, music players, games, and internet access. Almost all mobile phones can send text messages using SMS. MMS lets you send photos, audio, and video files. As phones got more features, many needed an operating system to run. Today, Google's Android and Apple's iOS are the most popular.

Before smartphones, companies like Nokia, Motorola, and Ericsson made mobile phones. Now, consumer electronics companies like Apple, Samsung, and Xiaomi also make them.

What Are Smartphones?

A smartphone with a touchscreen, held sideways.

As of 2022, most mobile phones are smartphones. A smartphone combines a mobile phone and a small computer in one device. Most smartphones use a graphical user interface and a touch screen. Many also have a voice assistant, like Siri on iPhones. You can use spoken commands to control the phone and interact with the internet. You usually type text using a virtual keyboard on the screen. Some smartphones have a small physical keyboard. Smartphones can access the internet through cellular networks and Wi-Fi. They can also connect directly to other devices using Bluetooth or cables like USB.

Smartphones can run apps, which gives them many more features than older mobile phones. With internet access and built-in cameras, smartphones make video calling easy. They also offer many web services and apps, like traditional computers. However, smartphones are often limited by their smaller screens and keyboards. Typically, smartphones have cameras, music players, web browsers, email, maps, GPS, and various sensors. Besides voice calls, smartphone users often communicate using SMS, MMS, email, and social media apps.

How Many People Use Mobile Phones?

In 2002, only 10% of the world's people used mobile phones. By 2005, this number grew to 46%. By the end of 2009, there were almost 6 billion phone users worldwide. This included 1.26 billion wired phones and 4.6 billion mobile phones.

Satellite Phones

An early Iridium satellite phone from the late 1990s.

A satellite phone, or satphone, is a type of mobile phone. It connects to other phones or the main phone network using radio links through satellites orbiting the Earth. Unlike cellphones, they do not need ground-based cell towers. This means they can work in most places on Earth, as long as they have a clear view of the sky and the satellite. Some systems cover the whole Earth, while others cover specific areas. Satellite phones offer similar features to regular mobile phones. They support voice calls, text messages, and basic Internet access. The main benefit is that they work where regular phone networks are not available.

Satellite phones are popular for trips to remote places, hunting, fishing, and humanitarian missions. They are also used in mining and other hard-to-reach areas. Satellite phones are rarely affected by natural disasters or wars. This makes them very reliable for emergencies when local communication systems might fail.

See also

In Spanish: Teléfono para niños