Why is ISDN used?

Answer 1

Why ISDN?

until 1980 networking system was dominant by analoge, with analog data communication only voice based apllications can be on, evaluation of humanity sceince lead to new aspect and new looks for next step, in 1980 they start to think about fully digital network in sence of new communation ability, sceintist think in ISDN it's appriviation for Integrated service digital network the meaning of integrated here means integrating more than one conventional service, i mean the integrate voice, data, voice and image processing and that not easy in analog.

ISDN working up houses phone line, meanwhile it make isolation between data and voice call, it's relible since it uses some protocols like x.25, LAPB and LAPD and x.25

in ISDN house you see every electrical indivitual has its own connection with ISDN modem, like phone, PC etc.

ISDN support varaity of speed there were different in technology applied some how per every indivitual contry like UK, US, Japan etc.

ISDN was the basic step for more furthere development in networking field.

the idea was behind ISDN is wise enough to make ISDN survive over decated, there idea was to make multi virtual channel in the same physical channel, those channels are controlled over x.25 protocol, LAPD and LAPD control D channels which is controller of the stream and user data the actual data stream send.

by combining those channel we can make an array of those channels that propotional to user need, cause in network every bit is coast supra money and bandwith.