# ISDN D-Channel The ISDN (Integrated Services Digital Network) D-Channel is a dedicated signaling channel used for establishing and managing communication sessions. It handles out-of-band signaling, carrying call setup and teardown messages separate from the actual voice or data transmission. Typically, the D-Channel operates at 16 kbps in Basic Rate Interface (BRI) configurations and 64 kbps in Primary Rate Interface (PRI) setups. This separation of signaling from data channels allows for more efficient communication management and dynamic allocation of network resources. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://isdn.learn-telecom.com/channels/isdn-d-channel.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.