Answer: ISDN ( Integrated service digital network)
Step-by-step explanation:
The integrated service digital network (ISDN) is defined as the set of standard communication for the simultaneously digital transmission of various types of data, voice and network services by using the PSTN ( public switched telephone network).
The ISDN facilitate various type of digital channels to the users. It also provide high data rate by using the digital schema. In integrated service digital network, the channels are operate concurrently in the copper wire.