<P> Telstra provides the business customer with the ISDN services . There are five types of ISDN services which are ISDN2, ISDN2 Enhanced, ISDN10, ISDN20 and ISDN30 . Telstra changed the minimum monthly charge for voice and data calls . In general, there are two group of ISDN service types; The Basic Rate services--ISDN 2 or ISDN 2 Enhanced . Another group of types are the Primary Rate services, ISDN 10 / 20 / 30 . Telstra announced that the new sales of ISDN product would be unavailable as of 31 January 2018 . The final exit date of ISDN service and migration to the new service would be confirmed by 2022 . </P> <P> Bharat Sanchar Nigam Limited, Reliance Communications and Bharti Airtel are the largest communication service providers, and offer both ISDN BRI and PRI services across the country . Reliance Communications and Bharti Airtel uses the DLC technology for providing these services . With the introduction of broadband technology, the load on bandwidth is being absorbed by ADSL . ISDN continues to be an important backup network for point - to - point leased line customers such as banks, Eseva Centers, Life Insurance Corporation of India, and SBI ATMs . </P> <P> On April 19, 1988, Japanese telecommunications company NTT began offering nationwide ISDN services trademarked INS Net 64, and INS Net 1500, a fruition of NTT's independent research and trial from the 1970s of what it referred to the INS (Information Network System). </P> <P> Previously, in April 1985, Japanese digital telephone exchange hardware made by Fujitsu was used to experimentally deploy the world's first I interface ISDN . The I interface, unlike the older and incompatible Y interface, is what modern ISDN services use today . </P>

Was designed as an alternative to the t-1 line