PRI vs. VoIP: A Quick Comparison of Two Telephony Systems

VOIP headset on laptop keyboardMost people are not aware of the fierce debate going on over PRI vs. VoIP. They may not even be aware that there is a difference. Although these two serve the same purpose, they are very different technologies. Primary Rate Interface or PRI came out in the 80s while VoIP became mainstream decades later. Many small businesses turn to VoIP, although PRI is still popular with many medium and large businesses. Which is the better system, then?


Back in the day of the plain old telephone service or POTS, it was hard to get a telephone line. Companies needed a way to expand their single telephone lines so more than one person could use it at a time. The PRI standard came along and did just that. It provided 23 channels for each physical circuit by passing it through a Private Branch Exchange or PBX. Each channel was a separate line. It was expensive, but it was worth it.


VoIP uses the Internet instead of POTS to transmit voice and other types of communication, and it does not need a PBX. VoIP comes in many forms, the most popular of which is the Session Internet Protocol or SIP. However, it does need a special type of phone to work, although SIP technology is also available through computers, tablets, and smartphones.

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Pros and cons

The biggest advantage of PRI over VoIP is the quality of the data transmission. Because it transmits over a telephone line, there is no data loss. This is important if reliable communications are critical to your business, such as a call center. If you use a VoIP protocol, you can expect some data loss at any time. However, setting up a PRI is much more expensive than VoIP. Unless you already have a PRI system in place, it is more cost effective to put in a VoIP instead.

There is no solid conclusion when it comes to PRI vs. VoIP. While VoIP is certainly easier and cheaper to put in, PRI is more reliable. The system you choose will depend on your needs.