What is ISDN?

If a person is too much tech-savvy, it is possible for him/her to know the details of ISDN. But there are lots of people who use the facilities of this service, but don’t have clear idea about what ISDN is. So, for their benefit, an explanatory definition is required. Basically, ISDN is the abbreviated form of Integrated Services Digital Network. It is an international communication standard where you can send video, voice mails, audio and data through normal telephone wires or digital telephone lines. There are mainly two types of ISDN- BRI and PRI.

Basic Concept on ISDN
Through ISDN, digital transmission has become easier. Here, the data and other video and audio are transmitted through the copper wire of telephone. Instead of using a telephone modem, the business organizations are installing ISDN adapter. The installation is not only limited to business houses. People are also setting it up in their houses because, here, you can receive web pages at 128 Kbps, while with a telephone modem; this speed is only 56Kbps. To access the ISDN system impeccably, the adapter must be on both sides of the transmission that means your service provider must keep an ISDN adapter. In large countries, the ISDN connection is provided by the phone companies. The unique version of ISDN employs baseband transmission. But there is another version of ISDN, known as B-ISDN. This system uses broadband transmission and support almost 1.5 Mbps transmission rate. In case of B-ISDN system, fiber optic cables are required. This system is not widely available till now. With the two level of services (BRI and PRI), ISDN is still holding its place worldwide.
Types of ISDN
Basically, there are two types of services provided by ISDN- BRI or Basic Rate Interface and PRI or Primary Rate Interface. Yes, there are some distinctive features of these two types, but the only similarity is that both rates require a number of B-channels and D-channels. What are the activities of these channels? The B-channels are responsible for carrying data and voices with other services, where, D-channels transmit control and signaling information.
1. Basic Rate Interface- This rate comprises of 2 B-channels of 64 Kbps and one D-channel of 16 Kbps. So, it is easier for a Basic Rate user to get 128 Kbps service. Generally, BRI is installed mainly at home or small business institutions.
2. Primary Rate Interface- This rate has a 64 Kbps D-channel with 23 B-channels. The number of B-channels varies from a country to other. Sometimes, the number of B-channels can be 30 too. Mainly, the PRI system is installed for larger usages at big organizations.
Something More on ISDN
With the technological advancement, the ISDN has stepped into the picture in 1990s and brought a revolution by providing the high-speed internet. Though, like its predecessor (the dial-up connection), ISDN was also operated through phone, it brought the concept of high-speed internet. Not only that, but it also make ways for the present DSL and Cable modem internet to make internet easily accessible.