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 −
The figure given below depicts 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.
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.