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Primary rate interface


What is a primary rate interface (PRI)?

The primary rate interface (PRI) enables enterprises to transmit voice and data through the integrated services digital network (ISDN). On a single phone line, it can accommodate up to 23 B channels. 

A PRI-enabled communications system allows several users to have extensions and numbers on a single line.

What is primary rate interface (PRI)

What are the functions of the primary rate interface?

Here are some functions that a primary rate interface can provide:

Direct inward dialing

The primary rate interface can be set up for up to 23 users in a company. This means anybody calling from outside the organization can reach their intended contact or department directly through a single line.

For big businesses, it is normal to have up to 50 users associated with a single PRI, which implies 50 different phone lines all operating over the same primary rate interface circuit at the same time.

Additional circuit

An additional PRI circuit can be acquired and connected to the existing system, allowing for an additional 23 channels for voice, data, or video transmissions.

As the company grows and expands, it is increasingly possible that additional conversations will take place at the same time.

What are the benefits of using a primary rate interface?

There are several benefits to using a primary rate interface, and these include the following:


Due to their dedicated line structure, high-quality calls performed over a primary rate interface are created considerably faster, which benefits your organization. 


Primary rate interface lines ensure reliability by empowering the central office. It allows them to remain operational during power outages.


Analog trunk lines are simple to connect if you have no technical skills since primary rate interfaces are digital. They also offer an extra measure of protection and privacy to your conversations.


PRI lines are adaptable since various channels can be used for communication or data, allowing more data to be transferred in a given period.

Straightforward billing

A single primary rate interface line saves time and money compared to purchasing 30 separate telephone lines and having them all installed and then terminated later.

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