mobile phone
The mobile phone or cell phone is a long-range, portable electronic device used for mobile communication. In addition to the standard voice function of a telephone, current mobile phones can support many additional services such as SMS for text messaging, email, packet switching for access to the Internet, and MMS for sending and receiving photos and video. Most current mobile phones connect to a cellular network of base stations (cell sites), which is in turn interconnected to the public switched telephone network (PSTN) (the exception is satellite phones).
History of mobile phone
telephone network is one global device: probably the biggest and most complicated machine on the planet. Despite its ubiquity, it is a fairly recent invention.
The telephone initially developed using the technology designed for the telegraph (invented by Wheatstone and Morse in 1837). It started out as a manually-switched network (the first telephone exchange was able to handle a whole 21 lines, and was installed in 1878).
Alexander Graham Bell patented the telephone in 1876, though there remains some dispute about whether the inventor's glory should really go to Elisha Grey, whose similar patent was only filed an hour or so later. There is some suggestion the crucial scribbled addendum 'variable resistance' in the margin of Bell's patent may have come from Grey's work.
In the next year, 1877, Western Union turned down an offer of the patent rights for the telephone for $100,000. A few years later, they had realised their mistake, and offered $25,000,000, but Bell refused to sell.
That same year, Thomas Edison demonstrated the phonograph. He had developed it as part of a telephone call transcription service, so that telephone messages could be delivered by telegraph: an early form of the emerging voice message to messaging services being offered today!
Calls were connected by operators. An American undertaker, Almon Strowger, discovered that the local telephone operators were unfairly connecting callers who asked for an undertaker to his rivals, so he decided to design an automatic telephone switchboard!
The first Strowger electro-mechanical automatic exchange went live in 1897, although in Britain it took another 70 years before all subscribers were connected to automatic exchanges.
Modern telephone exchanges are really more like specialist computers, and there are fewer and fewer of them around: the intelligent parts of the switching is done in fewer, larger units.
What used to house a telephone exchange now only holds a "concentrator" where telephone lines are connected to the network.
As with the internet, for telephones, location is increasingly unimportant.
The telephone initially developed using the technology designed for the telegraph (invented by Wheatstone and Morse in 1837). It started out as a manually-switched network (the first telephone exchange was able to handle a whole 21 lines, and was installed in 1878).
Alexander Graham Bell patented the telephone in 1876, though there remains some dispute about whether the inventor's glory should really go to Elisha Grey, whose similar patent was only filed an hour or so later. There is some suggestion the crucial scribbled addendum 'variable resistance' in the margin of Bell's patent may have come from Grey's work.
In the next year, 1877, Western Union turned down an offer of the patent rights for the telephone for $100,000. A few years later, they had realised their mistake, and offered $25,000,000, but Bell refused to sell.
That same year, Thomas Edison demonstrated the phonograph. He had developed it as part of a telephone call transcription service, so that telephone messages could be delivered by telegraph: an early form of the emerging voice message to messaging services being offered today!
Calls were connected by operators. An American undertaker, Almon Strowger, discovered that the local telephone operators were unfairly connecting callers who asked for an undertaker to his rivals, so he decided to design an automatic telephone switchboard!
The first Strowger electro-mechanical automatic exchange went live in 1897, although in Britain it took another 70 years before all subscribers were connected to automatic exchanges.
Modern telephone exchanges are really more like specialist computers, and there are fewer and fewer of them around: the intelligent parts of the switching is done in fewer, larger units.
What used to house a telephone exchange now only holds a "concentrator" where telephone lines are connected to the network.
As with the internet, for telephones, location is increasingly unimportant.
the advantage of mobile phone
There are so many advantages of using a mobile phone. Many people use a mobile phone as a very important device for getting information. Also some people use a mobile phone to know the new news. In addition, government uses a mobile phone to spread the consciousness between people in different types of life. Some people use the mobile phone in business. For example, they use it for shopping. Many companies use mobiles to advertise their goods. Also, making mobile phone improves the economy of the country. When making mobiles, workers get new experiences and get more salary as they work hard. In addition, the factory which makes mobiles will need more employees, so more jobs will be offered. The workers live will be better. The factory will produce more mobile devices and then export them to other countries. The country may earn lots of money. Therefore, the country can use this money to develop it facilities. The mobile phone is helpful and 98% said the mobile phone is easy to use. Most people prefer to use Nokia _one of the phone types. I accept that the mobile phone help people to communicate with their friends when they are in another country. Also we can use SIM card in any mobile. We can use mobile phone in our study, for example; if we want to store our information in the mobile memory. In addition, we can send a message, take some pictures & videos.
The disadvantage of mobile phone
The mobile phone, although it is a useful devise, also negatively affects our life. For examples, calls in mobile phone are more costly than land phones. Some people use a mobile phone to destroy others mobiles by viruses programs. It causes diseases for eyes, ears and brain when the people use it for along time. For example, the SAR is the rate at which the body absorbs emissions from the phone handset. Sometimes the mobile phone makes problems between people. Some use a mobile phone in impropriate places such as libraries, when they are at school or university. Few people said the mobile phone is difficult to use.
