What does ISDN mean in mobile Internet settings?

ISDN (Integrated Service Digital Network) Chinese name is integrated service digital network, which is the abbreviation of the telecommunications network of digital exchange and digital transmission, and China Telecom commonly calls it"One-stop service"。

ISDN is a communication network developed on the basis of the best integrated digital network, which can provide end-to-end digital connection, can carry voice and non-voice services, and users can access the network through multi-purpose user --- network interfaces. ISDN adopts digital transmission and digital switching technology to integrate various services such as **, fax, data, and image into a unified digital network for transmission and processing, and provides users with two interfaces: basic rate (2B+D, 144Kbit S) and primary group rate (30B+D, 2MbitS). The basic rate interface consists of two independent B channels (64 kbits) and one D channel (16 kbits).

Channel B is generally used to transmit voice, data and images, and channel D is used to transmit signaling or packet information.

ISDN can provide users with three types of services: bearer services (regardless of the type of user terminal); User terminal services (such as digital, four-class fax, data communication, communication, etc.); Abundant supplementary services (such as the identification and display of the main and called user numbers, call waiting, call forwarding, multi-user numbers, sub-addresses, three-party communication, etc.).

ISDN refers toIntegrated Services Digital Network(Integrated Services Digital Network, ISDN) is an international standard for digital networks and is a typical circuit-switched network system.

In the ITU proposal, an ISDN is a communications network developed on the basis of a digital network IDN, providing end-to-end digital connectivity to support a range of services (including voice and non-voice services), providing users with a multi-purpose standard interface to access the network.

The integration of communication services is to use a single user line to provide a variety of services such as fax, video, and data communication.

1. ISDN is an all-digital network that realizes end-to-end digital connectivity. The modern network adopts digital program-controlled switches and digital transmission systems. Processing inside the network has been fully digitized, but voice services are still available through the user interface.

on analog signal transmission. In ISDN, the user loop is also digitized.

2. ISDN realizes end-to-end digital connection, which can support voice, data, image and other services, and is a comprehensive service network. Theoretically, any form of raw signal can be converted into a digital signal.

ISDN can be used to transmit and exchange information between users. Multiple user terminals can be connected to the same interface, and different terminals can be used at the same time.

The demo model of the big eggplant family is not included: iPhone 12 && Huawei P40 && Xiaomi 11 The system version refers to the integrated service digital network, which is an international standard for digital networks and a typical circuit switching network system. In the ITU proposal, ISDN is a communication network developed on the basis of digital network IDN, and ISDN can support a variety of services, including ** business and non-** service.

This method works for Xiaomi, Apple, Huawei.

ISDN specific content: There are two types of ISDN terminals: one is a terminal that conforms to the ISDN user network interface protocol, called TE1, and the other is a terminal that does not comply with the ISDN user network interface protocol and is connected to the ISDN by adding a terminal adapter (TA), called TE2.

TE1 is a terminal with protocol processing, maintenance, interface control functions and extended functions for connecting other devices, such as digital terminals, visual terminals, multi-roll function terminals and four types of fax machine (G4) terminals.

From the perspective of the functional composition of the device, TE1 actually contains two functions: one is to implement the interface function with the ISDN according to the user network interface protocol of CCITT on ISDN; The second is to realize various communication and processing functions related to the application of terminals.