What type of data transmission is characteristic of ISDN?

ISDN, which stands for Integrated Services Digital Network, is characterized by digital data transmission. This technology was developed to allow for simultaneous transmission of voice, video, and data over traditional telephone networks while securing higher quality and faster speeds compared to the analog systems that were widely used before its introduction.

Choosing digital as the correct answer underscores that ISDN primarily operates using digital signals, which convert the data into a format suitable for transmission over digital lines. This results in clear, uninterrupted communication channels that can facilitate multiple services like telephony and data transfer at the same time, enhancing the overall functionality and performance of the network.

Other forms of data transmission, like analog, involve continuous signals that can be subject to noise and distortions, making them less suitable for high-quality communication needs. Hybrid signifies a mix of both types without defining a clear characteristic, which does not align with ISDN's specific and standardized use of digital technology. Wireless pertains to transmission methods that employ radio waves or other wireless technologies, which is also outside the purview of ISDN, as it is fundamentally based on wired connections. Thus, identifying digital confirms the essential characteristic of ISDN as a technology designed for efficient, high-quality communication.