Summary：

　　·PSTN is enable to support data &picture services.

　　·More different networks are needed to be built due to more different services would be provided by Telecommunication Bureau.

　　·Subscriber is not convient to apply and use.

　　·So， a communication network which can support voice、 data and picture etc at same time are required ，ISDN network is just that one.

　　ISDN Developments in China：

　　· China began to do scientific research on ISDN in the early years eighties.

　　· Before 1995，ISDN was developed slowly in China， it was mainly in a trial run period.

　　· In 1996 MPT issued a plan to make a test on ISDN around 22 cities of the whole country.

　　· Shanghai opened local ISDN in 1996，the target of 10，000 lines would be reached this year.

　　·Beijing officially opened local ISDN on Oct，14，1997.

　　·Nanjing、Shenyang、Sichuan、Heilongjiang、Hunan、Shandong etc、the main provinces and cities of the whole country are going to open ISDN services to society this year.

　　·Shenyang is going to open ISDN service to society on Aug 1，1997，detail destinations are 2386、2383、2484、2389， the other districts will be opened on Sep，30.

　　·On Nov，1997，MPT convened ISDN general mobilization to total P&T in Beijing .

　　·MPT drawn up the main target of next three years to increase ISDN with intelligent network.

　　·Defined ATM as the central network of 169 project，ISDN as it's general frame structure of access network.

　　·Defined the target of infiltration rate of ISDN line in the range of whole country this year 1% for local telephone lines.