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Telephone Introduction:A long-distance communication device that can transmit and receive voice

TIME : 2022-11-17 HITS : 43

Telephone Introduction:A long-distance communication device that can transmit and receive voice

1 basic functions



The telephone set is set on the user side of the starting point and the end point of the telephone communication, and is the user terminal equipment of the telephone network. Modern telephones can conveniently realize calls and conversations between end users, which have been formed after many people's research and countless improvements for more than one hundred years. Although their styles vary widely, they generally have the following basic functions:

1. Acoustic and electric interchange

Because it is necessary to carry out fast and long-distance communication, the sound cannot be transmitted directly, but the sound must first be converted into an electrical signal (that is, electricity is used as a carrier), and then the electrical signal is restored to sound after reaching the other party.

2. Off-hook identification

When the calling party picks up the phone, the switch should have the function of knowing "someone wants to call", so that the switch is ready to connect.

3. Send a signal

The automatic telephone set directs the work of the telephone exchange by sending a dial signal, and then establishes a connection between the two telephone sets.

4. Ring the bell

That is, when the other party calls, the telephone can tell the owner with a ring tone: "Someone is calling."

5. Electric connection

In the telephone, the components that realize these five functions are: handset, cradle, dial (or keypad), telephone bell and telephone circuit.


2 main categories

wired telephone

The telephone has the function of converting the sound wave of the terminal into an electronic signal, transmitting it to the remote party through the telephone line, and regenerating the electronic signal transmitted by the other party into voice (sound wave) to make it talk. The selected signal (dialing pulse), informing the other party of the call tone and other functions. The telephone is composed of a transmitter that converts voice into electric current and sends it to the telephone line, a receiver that restores the current transmitted by the other party to voice, a dial or button to call the other party, and a ringtone that sends the calling tone. These connections are performed on the telephone line Its functional line network and other components. There is a small box filled with carbon particles inside the transmitter, and a thin hard aluminum alloy vibrating plate is placed in front of it. The vibrating plate vibrates and vibrates carbon particles according to the voice, and the carbon particles conduct current. With the contact degree of the particles, the resistance changes to generate voice current. After receiving the voice current of the other party, the receiver generates a magnetic force caused by the voice current on the coil, vibrates the iron vibration plate, and emits a sound.

wireless phone

wireless loop - cordless phone

telephone handset

digital cordless phone

analog cordless phone

mobile phone

PHS (wireless phone)



With the continuous rapid development of IT technology, the processing ability of embedded terminal equipment is getting stronger and stronger. At the beginning of the 21st century, a telephone "smart phone" with a personal data assistant (PDA) appeared.

In addition to complete fixed-line functions, smart phones usually have large-capacity business card management functions, incoming and outgoing call management functions, phone harassment prevention (telephone firewall) functions, enterprise group telephone business card (internal business card) management functions, and auxiliary office functions. Many functions of , such as: schedule, note, calendar, calculator and other functions. Early smart phones had certain information exchange capabilities through dial-up Internet access, and realized the functions of sending short messages and receiving text messages. With the development of fixed-line smart phones in China for nearly ten years, their processing capabilities have been strengthened, and the functions of smart phones (Smartphone) have been gradually increased.

Smart phones already have the ability to surf the Internet and strong multimedia functions. It can browse the web, play audio and video, and has functions such as e-books and electronic photo frames. At the same time, the functions of smart phones in auxiliary office, auxiliary marketing, entertainment and other aspects have also been greatly enhanced. On the basis of overturning the traditional fixed telephone, more business functions and PDA functions are realized.


3Use environment

Conditions of Use

Ambient temperature: -10~40

Relative humidity: 45%~95%

Atmospheric pressure: 860~1060mbar

Environmental noise:60dB(A)

technical performance

1. Working frequency: 300~3400HZ

2. Pulse on-off ratio: 1.6±0.2:1

3. Frequency deviation of dual-tone dialing:≤±1.5%

4. Dual audio signal level:Low frequency group: -9±3dB;High frequency group: -7±3dB;The high frequency component in the frequency combination is 2±1dB higher than the low frequency component

5. Ringing sound level:70dB(A)

6. Electroacoustic performance:

At 0 kilometers, the objective sending reference equivalent is+3; at 3 kilometers, the objective sending reference equivalent is+15; at 5 kilometers, the objective sending reference equivalent is+15.

At 0 kilometers, the objective receiving reference equivalent is-5; at 3 kilometers, the objective receiving reference equivalent is+2; at 5 kilometers, the objective receiving mixed test equivalent is+2.

At 0 kilometers, the objective sidetone reference equivalent is+3; at 3 kilometers, the objective sidetone reference equivalent is+10; at 5 kilometers, the objective sidetone reference equivalent is+10.


7 Future development

The development of high-tech telephones is formed with the development of wireless communication. The development trend of the telephone has developed to the IMT-200 service that can use satellite communication after the Digital telephone and PCS. IMT-200 supports high-speed transmission of information, multimedia services such as Packet and portraits. In the future, all voice calls, direct circuits for telegraph users, paging and e-mail can be used in all parts of the world; with the popularity of e-mail, the network is also becoming increasingly popular. VoIP is an unstoppable development trend. Existing landline telephones can no longer provide people's needs. Future landlines will be equipped with cameras and colored liquid crystal displays, so that we can see both sides when we answer the landline.


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We manufacture most of the parts by ourselves(handset,keypad,hanger etc).We have all kinds of machines doing moulding,injection,die casting,hardware machining.Our telephones are widely used in oil exploitation,chemical industry,prison,tunnel etc.As a reliable supplier , we can provide you with high-quality products and good after-sales service.

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