What are the different types of ISDN?

ISDN stands for integrated service digital network. It is a telephone switched network which integrates voice and data over a digital line simultaneously. It also provides packet switched networks.

ISDN supports a variety of services which are as follows −

• Voice calls
• Video texts
• Electronic mail
• Database access
• Facsimile
• Teletext
• Data transmission and voice
• Connection to internet
• Electronic Fund transfer
• Image and graphics exchange
• Document storage and transfer
• Audio and Video Conferencing

The figure given below depicts ISDN −

Channels of ISDN

ISDN has mainly three channels, which are as follows −

• B-channel − It offers a speed of around 64kbps, which can be used for home purpose.

• D-channel − It offers speeds ranging from 16 to 64 kbps. It is used in signaling of B channel. It offers data in small amounts.

• H-channel − It offers a range of speeds 384kbps, 1536kbps, 1920kbps. It is used in large organizations where high speeds are required.

Access Interfaces

There are several access interfaces to the ISDN, which are as follows −

• Basic rate interface −It allows us to send small amounts of data at lower speeds.

• Primary rate interface − It allows us to send large amounts of data at higher speeds.

• Broadband ISDN − It relies on fibre optics. we can send data at extremely high speed from one place to another. It is highly reliable.

• Narrow band ISDN − It is used for sending small data over long distances like telecommunications.