PRI stands for primary rate interface, and this technology has been around since the 1980s. What is PRI technology, and why has it survived so long in a world where networking and telephony evolve so quickly?

What is PRI and why is it used?

PRI is an end-to-end communication circuit that allows a single line to handle up to 23 concurrent transmissions. Each transmission could be voice, data or even video traffic. The communication takes place on a physical PRI circuit, which is made from two pairs of copper wire.

Why is PRI technology so popular?

In the very early days of telephony, there were party lines, a circuit that would transmit voice calls to each phone connected to it. Later, individual properties got their own phone lines, but they had limited bandwidth. If someone connected to the internet, the line couldn't be used for voice calls, for example.

That issue led to the creation of PRI, allowing businesses to have multiple concurrent connections on what otherwise appears to be a single line. This makes large-scale business phone systems easier to manage.

Each channel on a PRI line has 64kb/s bandwidth, and a PRI circuit can be used to join two private branch exchanges together, increasing the number of available lines even more. These lines made a lot of sense for rapidly expanding businesses in the 80s, 90s and early 2000s.

PRI lines can be based on T1 or E1 connections. These technologies are fairly similar in terms of the speeds of each channel. E1 lines are commonly found in Europe and Asia. They're slightly faster overall and have more available channels. T1 connections are most frequently seen in America.

PRI phone communication vs. SIP trunking

Today, there's less need for PRI technology because the traditional telephone system is rapidly being replaced by digital systems. Copper phone lines are falling out of use, and cable or fiberoptic lines are taking over, combined with IP telephony. These technologies allow businesses to run dozens, or even hundreds, of lines on a single connection.

It's much easier to scale your contact center when you've got a high-speed connection and use VoIP for all your communication needs. SIP trunking is a relatively easy and scalable way of making use of digital communications. With SIP trunking, a business uses its internet connection for VoIP and rents virtual lines from a service provider.

Even with SIP trunking, it's useful to have a Plain Old Telephone System line or a PRI connection as a backup for emergencies, depending on the size of your business and how critical your communication systems are.

Which is best for your business?

Deciding which system to use for your business can be tricky. With PRI, you're paying for a fixed number of lines, whether you're using them all or just a few of them. With SIP trunking, you often have the option of paying per line, which can be more economical if you don't need a lot of lines but may be inconvenient for medium-sized businesses.

Cloud VoIP solutions offer a convenient compromise, freeing businesses from the overhead of running their own PBX and potentially offering cost savings, too. If you'd like to know more about the different business communications solutions and cloud services available, contact the 8x8 team to request a demonstration.