Question: isdn uses b & d channels. what is d channel use for?
Evidence: ISDN offers two types of channels: A 64-Kb/s Bearer (B) channel used for data, and a 64-Kb/s (maximum) Delta (D) channel used for signaling and control over layers 1, 2, and 3 of the Open Systems Interconnection (OSI) model.
Answer: control and signaling information
data
carries control and signaling information