On Demand Demos
illustration of woman on computer screen on top of a cloud

Looking for more information on SIP trunking? In this guide, we’ll break down the basics of SIP trunking and how exactly it can benefit your business.

SIP Trunking vs. VoIP

Before we get started, here’s a primer on the key terminology:

VoIP (Voice Over Internet Protocol): A broad term used to reference phone calls made over internet data connections instead of using traditional phone lines.

SIP (Session Initiation Protocol): A protocol used to initiate, maintain and terminate communication sessions in VoIP applications. In other words, a sub-protocol that enables VoIP.

What is SIP Trunking?

SIP trunking is a way for you to eliminate your traditional phone provider, while keeping the phone system you already have. Instead of using a conventional phone line, it allows you to operate your entire phone system over the internet.

The Specifics

SIP is the technology that’s used for establishing, modifying, and terminating a voice communication session over the internet. The “trunking” part refers to the virtual link between your private business telephone network or Private Branch Exchange (PBX) and traditional phone network, using an internet connection.

In layman’s terms, SIP trunks replace your phone lines with the internet service you already have.

The History

Prior to SIP becoming a reliable means of carrying calls, telephone calls were carried over the Public Switched Telephone Network (PSTN). It works by using physical phone lines hardwired to businesses and homes and connecting them to a switching center where the calls are then connected to each other.

How Does SIP Trunking Work?

Unlike a traditional analog phone, a SIP trunk is a “virtual” phone so no hardwired lines are needed. Using SIP trunks, a provider (like Broadvoice) can connect multiple channels to your private PBX, allowing you to make and take phone calls all over the internet.

With SIP trunking, calls are routed through an existing VoIP or PBX system using a packet switch network. Voice calls are converted into packets of data and transmitted across the internet. When a call arrives, the packets of data are converted back to their original form, allowing you to take the call.

The process a SIP Trunking communication takes from your existing device, to your PBX, to a SIP trunk, to allowing calls via the internet.

Enabling VoIP through SIP trunking typically requires a SIP-compatible PBX (often called an IP PBX) or unified communication (UC) platform. Businesses can use a mix of desktop phones, softphones and mobile devices to promote greater mobility and allow those devices to all work from the same number—a huge benefit in our new remote-first world.

Who Needs SIP Trunking?

If you have an on-premise phone system, this is a great option for you! It’s the perfect way to replace your expensive dial tone and upgrade to basic cloud features without sacrificing your investment.

 If you’re still not convinced, check out some of the key benefits SIP trunking offers:

Cost Savings

SIP trunking significantly reduces the cost of business communications and can save you up to 70% compared to legacy phone providers. SIP limits the amount of time calls travel over networks, which reduces charges. These savings can be monumental especially for businesses with a heavy long distance call load. Furthermore, SIP trunking helps eliminate or reduce your landline rental fees. With SIP, you only buy what you need, unlike the bundle-based purchasing associated with PBX. Overall, SIP is a cost-effective way to not only preserve, but to maximize your investment in your existing PBX.


SIP trunks allow you to scale instantly. If you have increased seasonal phone traffic, you can immediately scale to meet your customer needs. For example, if you’re a small bakery that sees increased call volume over the holidays, you can easily add more channels to accommodate the calls during the holidays, and reduce the number of channels during other seasons. This allows you to pay for what you need—and only when you need it.

Greater Flexibility

SIP Trunks remove the location-based restrictions on telecommunications, so you’re free to choose any phone number regardless of location. If your business operates globally, this is huge! It gives you the ability to get a virtual phone number with a local phone code. This means customers can contact your business using the local option rather than the more expensive international option.

Unified Communications

As your devices—home phones, mobile phones, office phones, office computers, home computers—continue to grow, it will be paramount to find a way to unite all your communications under one solution. SIP trunking makes this possible with the creation of one address for every device. Instead of sorting through a variety of numbers, anyone attempting to contact you can simply use the SIP address of record.

Getting Started

It’s important to choose your SIP trunking provider wisely! This role will be integral in helping your organization integrate the technology and manage your communications over the long term. If you choose the wrong partner, your integration may be slower and your management could suffer over the long-term.

Luckily, here at Broadvoice, we understand this more than most. We value relationships and consistent communication and our goal is to help your company improve its communications while saving money in the process. If this sounds like a great proposition to you, let’s chat.

For even more information on SIP trunking, check out our in-depth white paper.

Be brilliant about the way you connect.

Our team loves to talk. Let’s chat about the VoIP solution that’s right for your business.

Related articles