The Telephone

The phone itself is a fairly simple device. A headset called a handset called a microphone and receiver is included in the handset. The microphone converts the sound into a direct electric analog transmitted as an electric signal, and the headset converts the received electric signal to sound. The switch hook judges whether the telephone is running current and informs the central office that the telephone is in use. The ring tone will respond to signals from the central office that will ring the phone.

The telephone network was an intelligent network that previously supported dumb devices (phones). All information in the telephone network and all services are included in the exchange of the telephone company. The phone on the table in the consumer's kitchen is just a speaker and a microphone. State-of-the-art TouchPhone is a very simple device, completely dependent on network services, but it can "request" by issuing the correct sound. In such an intelligent network, there is no room for innovation at the end. Of course, you can make the phone look like a cheeseburger or banana, but you can not change the service you offer. These services are completely dependent on the central exchange owned by the telephone company. Centralized innovation means slow innovation. It also means innovation led by the goal of a single company. Therefore, any content that seems not to satisfy the vision of a company with a network is denied or even actively opposed.

Using analogy: The network outlet is like a wall phone jack; it connects your phone to the outside world. "Binding" a network socket to an address (host and port) behaves just like a telephone company assigns a phone number to your home. Telephone socket in the house. ^ "SOCK_DGRAM" tells the kernel that you want UDP. When interacting with a socket in C, calling the socket () function will return a "file descriptor". Unix-like systems are known to handle many different things (including sockets) as if they were just files.

A business telephone system is a system in which the CO line used can directly control the important telephone system from a plurality of telephone stations and such systems typically provide related call processing so that a plurality of telephone stations It is different from setting up. Additional functions. The company's telephone system is generally divided into key telephone systems and private branch exchanges, but there are many hybrid systems. The key telephone system is initially different from a private branch exchange (PBX) in that it does not require operator or switch staff to establish a connection between a telephone exchange and a station or between stations. Technically, a private branch office shares that line with the telephone system of the central office. The capacity and function of a telephone system is equivalent to a telephone system of a larger system or a more complicated system.