AA 5 or 7 batteries
Landline phones use the vibration of sound to use the microphone in the phone to modulate the current and voltage on the telephone line, that is, to convert the sound into a voltage signal through the telephone line. It is transmitted to the other end of the phone, and then a microphone is used to convert the voltage signal into a sound signal. Because it is usually fixed in one location, the academic name is a landline phone, which is also commonly known as a landline phone.
Phones generally use AA or AA batteries. Both wired phones and wireless phones have batteries, but the batteries in newer landline phones are rechargeable. You don't need to replace the batteries yourself. You can just use a charger to charge them when they run out of power. If you only need to answer calls, you can still make normal calls without putting in the battery, but functions such as caller ID and hands-free will not work properly.
Landline telephone, one of the greatest inventions in human history
Since its birth, human beings have never stopped innovating communication technology. From beacons on old watchtowers to artificially trained homing pigeons, people have tried every means to speed up communication. But it was not until the past two hundred years, after people gradually understood how to use electricity, that the progress of human beings in communication technology can be described as "rapid progress".
In 1793, the French Chape brothers set up a 230-kilometer-long bracket line between Paris and Lille to quickly deliver messages through signaling tower relays. In 1796, Hughes proposed a method of transmitting voice messages via microphone relay, and called this communication method Telephone, and this familiar word was born.
In 1837, the American Morse designed the Morse code, which uses different combinations of "dots", "dashes" and "spaces" to represent letters, numbers, punctuation and symbols. On May 24, 1844, he personally controlled the telegraph machine and sent the world's first telegram in the chamber of the Federal Supreme Court in the Capitol Building in Washington.
On February 14, 1876, Bell applied for a telephone patent at the U.S. Patent Office. On June 2, 1875, he connected a metal piece to an electromagnetic switch in an experiment, and the sound magically formed an electric current. However, there have always been different opinions about the inventor of the telephone. Until 2002, the U.S. Congress confirmed that the inventor of the telephone was Antonio Muzzi.
After Bell and others, various inventors successively launched their own research results and made various improvements to the telephone. A large number of patents were applied for, such as automatic dialing system, dry battery application, loading The application of coils, the invention of electronic triodes, etc. On January 25, 1915, the first interborough telephone line opened between New York and San Francisco.
On July 1, 1948, the transistor was invented, and telephone technology advanced rapidly. In 1956, a telephone cable was laid under the Atlantic Ocean between the United Kingdom and Canada, making long-distance intercontinental telephone communications a reality. However, China's telecommunications system was still developing slowly at this time.