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Primary Rate Interface (PRI)

Primary Rate Interface (PRI) is a telecommunications standard for carrying multiple DS0 voice and data transmissions between a network and a user in Integrated Services Digital Network (ISDN) environments.

PRI is typically used by enterprises and is a popular choice for connecting a Private Branch Exchange (PBX) to a public switched telephone network (PSTN). 

  • Multiple Channels: A standard PRI line in North America provides 23 bearer (B) channels and one data (D) channel, often referred to as 23B+D. Each B channel carries a voice call or data at 64 Kbps, while the D channel (64 Kbps) is used for signaling and control.

  • Higher Capacity: PRI lines offer a higher capacity than basic analog lines, making them suitable for businesses with higher call volumes or the need for advanced telephony features.

  • Direct Inward Dialing (DID): With PRI, businesses can have a range of telephone numbers without needing a physical line for each number. This is known as Direct Inward Dialing, allowing for direct calling to extensions within an organization.

  • Reliability and Clarity: PRI lines are digital, offering better voice clarity and reliability compared to traditional analog lines.

  • Integrated Voice and Data: PRI allows for the integration of voice and data traffic on a single line, which can be advantageous for businesses requiring both services.

  • Scalability: While offering multiple channels, PRI lines can be scaled according to business needs, adding or removing lines as required.

PRI is particularly suited for medium to large businesses with high communication needs, offering a reliable and efficient way to manage large volumes of voice and data traffic.

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