1.7. Internet-телефония

Постоянное совершенствование сети Интернет и ее повсеместное распространение привело к появлению принципиально нового вида связи, основанного на использовании Интернет протоколов и IP-серверов, преобразующих привычный голосовой сигнал в цифровой формат. Такая связь получила название IP или VoIP телефония.

В настоящее время все больше пользователей по всему миру предпочитают IP телефонию (VoIP телефонию) традиционным видам связи, благодаря двум весомым преимуществам:

Доступным тарифам, позволяющим экономить на совершении как местных, так и междугородних, международных звонков.

Высокому качеству связи без помех и посторонних шумов, а так же без потери данных в процессе общения.

К дополнительным возможностям IP телефонии можно отнести переадресацию вызова на мобильный или городской номер (в том числе и международный), услугу конференц-связи, позволяющую общаться одновременно трем и более абонентам, а также обмен видеорядом в режиме онлайн (видео-чат).

IP телефония устанавливает соединение по схемам: компьютер-компьютер, компьютер - стационарный номер и стационарный номер - стационарный номер. При использовании последней, аппарат должен доукомплектовываться специальным шлюзом.

Шлюз (другое название – сервер) связан как с телефонными линиями (благодаря чему возможен дозвон на любой номер в мире), так и с Интернетом (за счет чего и происходит подключение к любому компьютеру, соединенному с сетью Интернет). IP телефония через интернет использует нетрадиционные каналы связи, поэтому голосовой сигнал, перед тем как передаться другому абоненту, проходит через несколько этапов. Сначала он переводится в цифровой вариант, который разбивается на пакеты, передающиеся через Интернет. Затем сигнал из цифрового снова переводится в голосовой формат. Email client – a program that allows the user to create and send messages and manage the messages (to view, organize, print, delete, etc.) from their own mailbox. Communication protocols e-mail clients to servers. Currently, the main protocols are: The SMTP (Simple Mail Transfer Protocol) provides message delivery from the sender to the recipient's mailbox. An important feature of the basic version of SMTP is the lack of means of user authentication, because to send mail is not required. So to send mail, it is theoretically possible to use any SMTP server. On the one hand, it is quite convenient because you can send messages in case your email server for any reason is not functioning. However, on the other hand, it allows to hide the source of spam - imposed messages that are unnecessary recipients (advertising, malicious messages that contain viruses, etc.). Given these problems, currently the SMTP Protocol developed extension that allows you to verify users and to block mail sending if the sender was not authenticated. POP3 (Post Office Protocol version 3) allows the email client to accumulated in the mailbox of the message. Protocol allows the to interact the client and server on stand-alone models. The main characteristics are: ensuring authorized access to the mailbox; the lack of support for creating folders within a mailbox and work with them. IMAP4 (Internet Message Access Protocol version 4) is a newer Protocol that provides a sample client messages from the mailbox. The Protocol allows the interaction at any of the three models of Autonomous, interactive, or disabled. The main characteristics of this Protocol are: Email client – a program that allows the user to create and send messages and manage the messages (to view, organize, print, delete, etc.) from their own mailbox. Communication protocols e-mail clients to servers. Currently, the main protocols are: The SMTP (Simple Mail Transfer Protocol) provides message delivery from the sender to the recipient's mailbox. An important feature of the basic version of SMTP is the lack of means of user authentication, because to send mail is not required. So to send mail, it is theoretically possible to use any SMTP server. On the one hand, it is quite convenient because you can send messages in case your email server for any reason is not functioning. However, on the other hand, it allows to hide the source of spam - imposed messages that are unnecessary recipients (advertising, malicious messages that contain viruses, etc.). Given these problems, currently the SMTP Protocol developed extension that allows you to verify users and to block mail sending if the sender was not authenticated. POP3 (Post Office Protocol version 3) allows the email client to accumulated in the mailbox of the message. Protocol allows them to interact the client and server on stand-alone models. The main characteristics are: ensuring authorized access to the mailbox; the lack of support for creating folders within a mailbox and work with them. IMAP4 (Internet Message Access Protocol version 4) is a newer Protocol that provides a sample client messages from the mailbox. The Protocol allows the interaction at any of the three models of Autonomous, interactive, or disabled. The main characteristics of this Protocol are: Email client – a program that allows the user to create and send messages and manage the messages (to view, organize, print, delete, etc.) from their own mailbox. Communication protocols e-mail clients to servers. Currently, the main protocols are: The SMTP (Simple Mail Transfer Protocol) provides message delivery from the sender to the recipient's mailbox. An important feature of the basic version of SMTP is the lack of means of user authentication, because to send mail is not required. So to send mail, it is theoretically possible to use any SMTP server. On the one hand, it is quite convenient because you can send messages in case your email server for any reason is not functioning. However, on the other hand, it allows to hide the source of spam - imposed messages that are unnecessary recipients (advertising, malicious messages that contain viruses, etc.). Given these problems, currently the SMTP Protocol developed extension that allows you to verify users and to block mail sending if the sender was not authenticated. POP3 (Post Office Protocol version 3) allows the email client to accumulated in the mailbox of the message. Protocol allows them to interact the client and server on stand-alone models. The main characteristics are: ensuring authorized access to the mailbox; the lack of support for creating folders within a mailbox and work with them. I Email client – a program that allows the user to create and send messages and manage the messages (to view, organize, print, delete, etc.) from their own mailbox. Communication protocols e-mail clients to servers. Currently, the main protocols are: The SMTP (Simple Mail Transfer Protocol) provides message delivery from the sender to the recipient's mailbox. An important feature of the basic version of SMTP is the lack of means of user authentication, because to send mail is not required. So to send mail, it is theoretically possible to use any SMTP server. On the one hand, it is quite convenient because you can send messages in case your email server for any reason is not functioning. However, on the other hand, it allows to hide the source of spam - imposed messages that are unnecessary recipients (advertising, malicious messages that contain viruses, etc.). Given these problems, currently the SMTP Protocol developed extension that allows you to verify users and to block mail sending if the sender was not authenticated. POP3 (Post Office Protocol version 3) allows the email client to accumulated in the mailbox of the message. Protocol allows them to interact the client and server on stand-alone models. The main characteristics are: ensuring authorized access to the mailbox; the lack of support for creating folders within a mailbox and work with them. IMAP4 (Internet Message Access Protocol version 4) is a newer Protocol that provides a sample client messages from the mailbox. The Protocol allows the interaction at any of the three models of Autonomous, interactive, or disabled. The main characteristics of this Protocol are: Email client – a program that allows the user to create and send messages and manage the messages (to view, organize, print, delete, etc.) from their own mailbox. Communication protocols e-mail clients to servers. Currently, the main protocols are: The SMTP (Simple Mail Transfer Protocol) provides message delivery from the sender to the recipient's mailbox. An important feature of the basic version of SMTP is the lack of means of user authentication, because to send mail is not required. So to send mail, it is theoretically possible to use any SMTP server. On the one hand, it is quite convenient because you can send messages in case your email server for any reason is not functioning. However, on the other hand, it allows to hide the source of spam - imposed messages that are unnecessary recipients (advertising, malicious messages that contain viruses, etc.). Given these problems, currently the SMTP Protocol developed extension that allows you to verify users and to block mail sending if the sender was not authenticated. POP3 (Post Office Protocol version 3) allows the email client to accumulated in the mailbox of the message. Protocol allows them to interact the client and server on stand-alone models. The main characteristics are: ensuring authorized access to the mailbox; the lack of support for creating folders within a mailbox and work with them. IMAP4 (Internet Message Access Protocol version 4) is a newer Protocol that provides a sample client messages from the mailbox. The Protocol allows the interaction at any of the three models of Autonomous, interactive, or disabled. The main characteristics of 1

Email client – a program that allows the user to create and send messages and manage the messages (to view, organize, print, delete, etc.) from their own mailbox. Communication protocols e-mail clients to servers. Currently, the main protocols are: The SMTP (Simple Mail Transfer Protocol) provides message delivery from the sender to the recipient's mailbox. An important feature of the basic version of SMTP is the lack of means of user authentication, because to send mail is not required. So to send mail, it is theoretically possible to use any SMTP server. On the one hand, it is quite convenient because you can send messages in case your email server for any reason is not functioning. However, on the other hand, it allows to hide the source of spam - imposed messages that are unnecessary recipients (advertising, malicious messages that contain viruses, etc.). Given these problems, currently the SMTP Protocol developed extension that allows you to verify users and to block mail sending if the sender was not authenticated. POP3 (Post Office Protocol version 3) allows the email client to accumulated in the mailbox of the message. Protocol allows the to interact the client and server on stand-alone models. The main characteristics are: ensuring authorized access to the mailbox; the lack of support for creating folders within a mailbox and work with them. IMAP4 (Internet Message Access Protocol version 4) is a newer Protocol that provides a sample client messages from the mailbox. The Protocol allows the interaction at any of the three models of Autonomous, interactive, or disabled. The main characteristics of this Protocol are: