ISDN BRI vs PRI Interface: Difference and Comparison

Telecommunication has played a wider role in the development of this modern world. The invention of the radio paved the way for a gigantic field which made huge leaps and tremendous improvements in sending and receiving messages or data worldwide.

While it took days to communicate a message to a nearby city, it took only a fraction of a minute to send and receive messages to any part of the world. Broadband internet connection, VOIP, and DSL are presently used everywhere in telecommunication.

Before Internet and VOIP (Voice Over Internet Protocol), ISDN (Integrated Service Digital) was popular in telecommunication due to its simultaneous transmission of video, data and voice on a digital line over a telephone network. ISDN spearheaded the transformation of the analogue telephone network to digital lines.

The two main types of ISDN were BRI (Basic Rate Interface) and PRI (Primary Rate Interface). Though BRI and PRI belong to the same category, they differ in the service they provide to their users.


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While BRI provided a low-cost service, PRI remained the main service due to its high performance and reliability.

Key Takeaways

  1. ISDN BRI (Basic Rate Interface) is a digital communication protocol that uses two B channels and one D channel for transmitting data and voice. In comparison, ISDN PRI (Primary Rate Interface) uses 23 B and one D channels.
  2. ISDN BRI suits small businesses and residential customers requiring basic voice and data communication services. At the same time, ISDN PRI is ideal for large businesses and organizations with high call volumes and data transmission needs.
  3. ISDN BRI provides lower bandwidth and limited data transmission rates, while ISDN PRI offers higher bandwidth and faster data transmission rates.

ISDN BRI vs PRI Interface

ISDN BRI (Basic Rate Interface) provides two 64 kbps bearer channels and one 16 kbps signalling channel. ISDN PRI (Primary Rate Interface) provides 23 or 30 64 kbps bearer channels and one 64 kbps signalling channel.

ISDN BRI vs PRI Interface

This data could give an overall idea of how fast the communication would be in PRI network as it transmits data at a rate of 1.536 Mbps (Megabytes per second) which is twenty-three times faster than BRI.

Comparison Table

Parameters of ComparisonBasic Rate InterfacePrimary Rate Interface
DefinitionIt is one of the two types of ISDN interface, primarily for small-scale and home usage.It is a telecommunication interface intended for medium and large business firms.
Number of Bearer ChannelTwo bearer channels.Twenty-three bearer channels in T-carrier and thirty bearer channels in the E-carrier interface
Number of Data ChannelOne data channelOne data channel in both E-carrier and T-carrier.
Transmission SpeedA maximum speed of 128 kbps.The maximum transmission speed of 2.94 Mbps in dual PRI.
FeaturesLow-cost.Higher transmission speed with greater reliability.

What is BRI Interface?

The basic rate interface is the primary ISDN interface used in home and small-scale enterprises. It is the basic level of service in the ISDN network.

BRI interface helped receive or send data from multiple users at a time. It has two bearer (B) channel and one data (D) channel.

Among the two B channels, one B channel is used to transmit the signal and another B for receiving the signal. The bearer channel helps in carrying voice and data.

Data channel helps in carrying signal and control information.

The b channel transmits the signal in a circuit-switch network, whereas the D channel transmits data with the help of packets. BRI uses a pair of single twisted wires for data transmission.

A single B channel can transmit data at 64 kbps, So it is visible that BRI cannot transmit data not exceeding 128 kbps.

The data channel can transmit data at a rate of 16 kbps. Despite being able to transmit data at a slower speed when compared to PRI, it was popular among household and small-scale firms due to its low cost.

BRI did not gain popularity among large enterprises due to its low speed and reliability. To be precise, BRI acts as a level for basic service.

BRI was primarily meant for subscriber lines in telephone service.

bri interface 1

What is PRI Interface?

PRI stands for primary rate interface. PRI was the main interface preferred for high-speed internet access during its introduction in the market.

There are two types of BRI carriers. They are T- carrier and E-carrier.

The T-carrier configuration has twenty-three bearer channels and one data channel. T-carrier configuration is generally used in America and Japan.

While E-carrier boasts thirty bearer channels and one data channel, the e-carrier configuration is used in Australia and the European region.

The main reason for its high-speed network connectivity is because of the communication channel it possesses. As the number of bearer channel increases, the transmission speed also increases.

There are twenty-three bearer channels, meaning the transmission speed will be approximately 1.536 Mbps. This high speed was the reason behind large firms preferring PRI to BRI.  

Though PRI was efficient and reliable, people started searching for other alternatives due to the high cost. This resulted in the broadband network and voice-over-internet protocol (VOIP).

Slowly ISDN (PRI and BRI) network started losing its sheen due to high expenses compared to its competitors. Nevertheless, the ISDN network still transmits high-speed internet without broadband connectivity.

pri interface

Main Differences Between BRI and PRI Interface

  1. The primary rate interface is the preferred mode of communication for a high-speed network compared to the basic rate interface.
  2. A basic rate interface was adopted in the household due to its low cost in service.
  3. The primary rate interface has higher reliability and performance in transmitting data when compared to the basic rate interface.
  4. Large companies adopt The primary rate interface mainly, whereas small-scale companies prefer a basic rate interface system.
  5. The introduction of broadband harmed the primary and basic rate interfaces, in which the basic rate interface suffered a lot more than the primary rate interface.
  6. The only advantage of a basic rate interface over a primary rate interface is the cost difference not overlooked by people looking forward to high-speed network access.
Difference Between ISDN BRI and PRI Interface
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