# PRI - Primary Rate Interface Primary Rate Interface (PRI) is a telecommunications standard used widely for carrying multiple voice and data transmissions between network and user. It is part of the Integrated Services Digital Network (ISDN) framework and consists of 23 bearer channels (B channels) for data plus one signaling channel (D channel) in North America and Japan (23B+D), while other regions typically use 30B+D. This setup allows for efficient and high-capacity digital communication, suitable for large organizations and enterprises with substantial telecommunication needs. PRI is commonly utilized for transmitting numerous simultaneous calls or data sessions across a single physical line. --- # 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/interfaces/pri-primary-rate-interface.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.