The Primary Rate Interface (PRI) is a telecommunications standard used to connect digital telephone lines to a private branch exchange (PBX). It typically consists of 23 voice channels and one data channel, allowing for multiple simultaneous calls over a single line. PRI is commonly used by businesses that require a reliable and efficient way to manage high call volumes. PRI operates over the Integrated Services Digital Network (ISDN), which ensures high-quality voice transmission. This interface is particularly beneficial for organizations that need to maintain clear communication and support various services, such as video conferencing and data transfer, alongside traditional voice calls.