SIP Trunking 101 – An Introduction to the Basics

SIP Trunking Technology 101The internet age has impacted just about every aspect of American life. It has changed how we shop, consume entertainment, work, and keep up with friends. It has also profoundly changed the way we communicate. This is true for businesses as well as consumers. Old fashioned business phone systems are being replaced by internet protocol enabled solutions with voice signals being transmitted over the internet rather than traditional telephone lines. This approach, known as SIP trunking technology, adds a host of capabilities and sharply reduces telecommunications costs.

Whether or not you are planning to implement SIP trunks soon, it is good to have an understanding of the basics.


SIP stands for Session Initiation Protocol and it is the core technology used for establishing a voice communication session over a data network, particularly the internet. You can think of SIP as the technology that sets the rules and establishes the language for internet based voice and other unified communications.

SIP Trunking Technology

A SIP trunk if a group of SIP channels. Each SIP channel manages a single incoming or outgoing telephone call.  When a call is established, the SIP channel routes the voice signal to the network that handles all telephone traffic worldwide. It is known as the Public Switched Telephone Network (PSTN). It makes it possible that any phone can dial any other phone.

Top Reasons to Consider SIP Trunking

Businesses are making the switch to SIP for a number of reasons, but the main driver is cost reduction. SIP trunks are often sold as “unlimited,” meaning that most local and long distance calls (within the US and most of Canada) don’t incur any toll charges. Not only does this reduce the cost of communications, it also makes monthly expenses more predictable. In addition, although a SIP trunk can have any number of channels, they are sold in increments of 1, meaning that businesses can get (and pay for) only exactly the number of channels they need. This is in sharp contrast to traditional PRI lines, which are sold in groups of 23.

In addition to cost savings, SIP trunks also make it easier to add unified communications capabilities, such as audio conferencing, video calls, and visual voicemail. And because the voice system uses the same internet connection as your data needs, there is only one network to manage and support.


There are big differences between SIP trunking providers, so look for one that has a pricing model that makes sense for your business. We don’t necessarily recommend choosing the cheapest provider, because you want to make sure that there are no hidden fees and that the vendor has a reliable and high-performing Tier 1 carrier network. (Our pricing is explained in detail here.)

PBX Compatibility

SIP trunking works with SIP enabled (also called VoIP enabled, or IP enabled) PBX solutions. However, it can also be used with older legacy PBXs or Key systems with the help of a device called an Analog Telephony Adapter (ATA).  SIP trunks can also be used with many hosted PBX solutions.

You don’t need to be a telecommunications expert to take advantage of SIP trunking technology. The best solutions come with easy-to-use control panels for administration, and detailed documentation on how you can configure your PBX to work with SIP. Look for a provider with a great track record and the ability to offer you a free trial. Once you find the right partner, you’ll be well on your way to enjoying reduced communications cost, and simplified network management.

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