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Telecom Terms For Your Office Phone System - Speros - Savannah, GA

Unless you work in telecommunications, the industry jargon may seem more like alphabet soup. However, if you have a business phone system, or are considering a new system for your business, you may wonder what all of these acronyms stand for. We’ve created this quick guide for you to reference with some of the most common telecom terms.

POTS (Plain Old Telephone Service)

Also known as analog lines, a POTS line is the standard telephone service used for home phones and fax lines (raise your hand if you still have one of these). They are a single line with a single number. If you have a small office, you probably use POTS lines.

VoIP (Voice over Internet Protocol)

This one may be the easiest of the bunch. We have found that when we say VoIP, people will proudly say “voice over IP!” If you have a hosted or on-premises IP-PBX phone system, your voice is changed to the same type of data that your computer uses. In fact, VoIP uses your computer network to connect to the outside world. Data can be sent digitally through the internet if you are using SIP trunks rather than over traditional analog phone lines.

PRI (Primary Rate Interface)

PRI’s are most often used in offices that need a larger quantity of telephone lines. We use 23 voice channels to provide you with digital access to the public switched telephone network from a PBX phone system. This is what gives you a dial tone. PRI channels can also be used to deliver inbound calls to VoIP phones if you have an IP enabled PBX.

SIP (Session Initiation Protocol)

Using VoIP technology, SIP trunking connects your IP-PBX system to the internet. This is similar to how a PRI channel connects your telephone system to regular phone lines. SIP allows your calls to go through a voice over IP service rather than over a traditional phone line and is what the majority of VoIP telephones use to communicate.

PBX (Private Branch Exchange)

A PBX system is a private telephone network. This type of system has an internal switching system. Think of the old school switchboards, but smaller and without an operator. Your PBX system allows users in your office to communicate internally with one another, make or receive calls from a shared group of outside lines (POTS, SIP, or PRI), and route calls to individual users in your office.

On-premises PBX

This refers to a phone system that resides at your location where you have a server inside of a network closet or in a telephone closet. All digital PBX systems are on-premises as well as on-premises IP systems. An on-premises IP system allows calls to go over traditional phone lines (POTS or PRI’s) as well as over the internet through SIP trunking.

Hosted PBX

A hosted PBX, also called an internet phone, virtual phone, or cloud phone, uses VoIP technology. Your telecommunications provider hosts and manages your phone system. The only equipment you have on your premises is your desk phones. They connect directly to a router or network switch.


IP based phone system and some modern digital phone systems come with an application that you can install on your computer or another device. The application allows you to make calls through your phone system from your device. A softphone allows for greater flexibility and mobility with your phone system.

DID (Direct Inward Dialing)

You probably associate your DID with your extension, but your DID is what allows people outside of your telephone system to call your office phone directly. They do this using your personal using 7 or 10-digit public phone number.

Telecom terms can seem confusing and overwhelming, especially when they are mostly acronyms. We hope this guide will help you understand these terms so you don’t feel lost when talking about your communications system.


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